AutoGen: Template File

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# 3. AutoGen Template

The AutoGen template file defines the content of the output text. It is composed of two parts. The first part consists of a pseudo macro invocation and commentary. It is followed by the template proper.

This pseudo macro is special. It is used to identify the file as a AutoGen template file, fixing the starting and ending marks for the macro invocations in the rest of the file, specifying the list of suffixes to be generated by the template and, optionally, the shell to use for processing shell commands embedded in the template.

AutoGen-ing a file consists of copying text from the template to the output file until a start macro marker is found. The text from the start marker to the end marker constitutes the macro text. AutoGen macros may cause sections of the template to be skipped or processed several times. The process continues until the end of the template is reached. The process is repeated once for each suffix specified in the pseudo macro.

This chapter describes the format of the AutoGen template macros and the usage of the AutoGen native macros. Users may augment these by defining their own macros. See section 3.6.4 DEFINE - Define a user AutoGen macro.

> 3.1 Format of the Pseudo Macro |  |
> 3.2 Naming a value |  |
> 3.3 Macro Expression Syntax |  |
> 3.4 AutoGen Scheme Functions |  |
> 3.5 Common Scheme Functions |  |
> 3.6 AutoGen Native Macros |  |
> 3.7 Redirecting Output |  |

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## 3.1 Format of the Pseudo Macro

The pseudo macro is used to tell AutoGen how to process a template. It tells autogen:

1. The punctuation characters used to demarcate the start of a macro. It may be up to seven characters long and must be the first non-whitespace characters in the file.

2. That start marker must be immediately followed by the marker strings "AutoGen5" and then "template", though capitalization is not important.

The next several components may be intermingled:

1. Zero, one or more suffix specifications tell AutoGen how many times to process the template file. No suffix specifications mean that it is to be processed once and that the generated text is to be written to stdout. The current suffix for each pass can be determined with the `(suffix)` scheme function (see section 3.4.36 ``suffix'` - get the current suffix).

   The suffix specification consists of a sequence of POSIX compliant file name characters and, optionally, an equal sign and a file name "printf"-style formatting string. Two string arguments are allowed for that string: the base name of the definition file and the current suffix (that being the text to the left of the equal sign). (Note: "POSIX compliant file name characters" consist of alphanumerics plus the period (`.`), hyphen (`-`) and underscore (`_`) characters.)

2. Comment lines: blank lines, lines starting with a hash mark [`#`]), and edit mode comments (text between pairs of `-*-` strings).

3. Scheme expressions may be inserted in order to make configuration changes before template processing begins. It is used, for example, to allow the template writer to specify the shell program that must be used to interpret the shell commands in the template. It can have no effect on any shell commands in the definitions file, as that file will have been processed by the time the pseudo macro is interpreted.

       (setenv "SHELL" "/bin/sh")

   This is extremely useful to ensure that the shell used is the one the template was written to use. By default, AutoGen determines the shell to use by user preferences. Sometimes, that can be the "csh", though.

   The scheme expression can also be used to save a pre-existing output file for later text extraction (see section 3.5.4 ``extract'` - extract text from another file).

       (shellf "mv -f %1$s.c %1$s.sav" (base-name))

4. Finally, the end-macro marker must be last. It must not begin with a POSIX file name character, and if it begins with an equal sign, then it must be separated from any suffix specification by white space.

It is generally a good idea to use some sort of opening bracket in the starting macro and closing bracket in the ending macro (e.g. `{`, `(`, `[`, or even `<` in the starting macro). It helps both visually and with editors capable of finding a balancing parenthesis. The closing marker may not begin with an open parenthesis, as that is used to enclose a scheme expression.

It is also helpful to avoid using the comment marker (`#`); the POSIXly acceptable file name characters period (`.`), hyphen (`-`) and underscore (`_`); and finally, it is advisable to avoid using any of the quote characters double, single or back-quote. But there is no special check for any of these advisories.

As an example, assume we want to use `[+` and `+]` as the start and end macro markers, and we wish to produce a ``.c'` and a ``.h'` file, then the first macro invocation will look something like this:

    [+ AutoGen5 template -*- Mode: emacs-mode-of-choice -*-
    h=chk-%s.h
    c
    # make sure we don't use csh:
    (setenv "SHELL" "/bin/sh")  +]

The template proper starts after the pseudo-macro. The starting character is either the first non-whitespace character or the first character after the newline that follows the end macro marker.

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## 3.2 Naming a value

When an AutoGen value is specified in a template, it is specified by name. The name may be a simple name, or a compound name of several components. Since each named value in AutoGen is implicitly an array of one or more values, each component may have an index associated with it.

It looks like this:

    comp-name-1 . comp-name-2 [ 2 ]

Note that if there are multiple components to a name, each component name is separated by a dot (`.`). Indexes follow a component name, enclosed in square brackets (`[` and `]`). The index may be either an integer or an integer-valued define name. The first component of the name is searched for in the current definition level. If not found, higher levels will be searched until either a value is found, or there are no more definition levels. Subsequent components of the name must be found within the context of the newly-current definition level. Also, if the named value is prefixed by a dot (`.`), then the value search is started in the current context only. No higher levels are searched.

If someone rewrites this, I'll incorporate it. :-)

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## 3.3 Macro Expression Syntax

AutoGen has two types of expressions: full expressions and basic ones. A full AutoGen expression can appear by itself, or as the argument to certain AutoGen built-in macros: CASE, IF, ELIF, INCLUDE, INVOKE (explicit invocation, see section 3.6.16 INVOKE - Invoke a User Defined Macro), and WHILE. If it appears by itself, the result is inserted into the output. If it is an argument to one of these macros, the macro code will act on it sensibly.

You are constrained to basic expressions only when passing arguments to user defined macros, See section 3.6.4 DEFINE - Define a user AutoGen macro.

The syntax of a full AutoGen expression is:

    [[ <apply-code> ] <value-name> ] [ <basic-expr-1> [ <basic-expr-2> ]]

How the expression is evaluated depends upon the presence or absence of the apply code and value name. The "value name" is the name of an AutoGen defined value, or not. If it does not name such a value, the expression result is generally the empty string. All expressions must contain either a `value-name` or a `basic-expr`.

> 3.3.1 Apply Code |  |
> 3.3.2 Basic Expression |  |

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### 3.3.1 Apply Code

The "apply code" selected determines the method of evaluating the expression. There are five apply codes, including the non-use of an apply code.

``no apply code'`
  This is the most common expression type. Expressions of this sort come in three flavors:

  ``<value-name>'`
    The result is the value of `value-name`, if defined. Otherwise it is the empty string.

  ``<basic-expr>'`
    The result of the basic expression is the result of the full expression, See section 3.3.2 Basic Expression.

  ``<value-name> <basic-expr>'`
    If there is a defined value for `value-name`, then the `basic-expr` is evaluated. Otherwise, the result is the empty string.

``% <value-name> <basic-expr>'`
  If `value-name` is defined, use `basic-expr` as a format string for sprintf. Then, if the `basic-expr` is either a back-quoted string or a parenthesized expression, then hand the result to the appropriate interpreter for further evaluation. Otherwise, for single and double quote strings, the result is the result of the sprintf operation. Naturally, if `value-name` is not defined, the result is the empty string.

  For example, assume that `fumble` had the string value, `stumble`:

      [+ % fumble `printf '%%x\\n' $%s` +]

  This would cause the shell to evaluate "`printf '%x\n' $stumble`". Assuming that the shell variable `stumble` had a numeric value, the expression result would be that number, in hex. Note the need for doubled percent characters and backslashes.

``? <value-name> <basic-expr-1> <basic-expr-2>'`
  Two `basic-expr`-s are required. If the `value-name` is defined, then the first `basic-expr-1` is evaluated, otherwise `basic-expr-2` is.

``- <value-name> <basic-expr>'`
  Evaluate `basic-expr` only if `value-name` is not defined.

``?% <value-name> <basic-expr-1> <basic-expr-2>'`
  This combines the functions of ``?'` and ``%'`. If `value-name` is defined, it behaves exactly like ``%'`, above, using `basic-expr-1`. If not defined, then `basic-expr-2` is evaluated.

  For example, assume again that `fumble` had the string value, `stumble`:

      [+ ?% fumble `cat $%s` `pwd` +]

  This would cause the shell to evaluate "`cat $stumble`". If `fumble` were not defined, then the result would be the name of our current directory.

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### 3.3.2 Basic Expression

A basic expression can have one of the following forms:

``'STRING''`
  A single quoted string. Backslashes can be used to protect single quotes (`'`), hash characters (`#`), or backslashes (`\`) in the string. All other characters of STRING are output as-is when the single quoted string is evaluated. Backslashes are processed before the hash character for consistency with the definition syntax. It is needed there to avoid preprocessing conflicts.

``"STRING"'`
  A double quoted string. This is a cooked text string as in C, except that they are not concatenated with adjacent strings. Evaluating "`STRING`" will output STRING with all backslash sequences interpreted.

```STRING`'`
  A back quoted string. When this expression is evaluated, STRING is first interpreted as a cooked string (as in `"STRING"') and evaluated as a shell expression by the AutoGen server shell. This expression is replaced by the stdout output of the shell.

``(STRING)'`
  A parenthesized expression. It will be passed to the Guile interpreter for evaluation and replaced by the resulting value.

  Additionally, other than in the `%` and `?%` expressions, the Guile expressions may be introduced with the Guile comment character (`;`) and you may put a series of Guile expressions within a single macro. They will be implicitly evaluated as if they were arguments to the `(begin ...)` expression. The result will be the the result of the last Guile expression evaluated.

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## 3.4 AutoGen Scheme Functions

AutoGen uses Guile to interpret Scheme expressions within AutoGen macros. All of the normal Guile functions are available, plus several extensions (see section 3.5 Common Scheme Functions) have been added to augment the repertoire of string manipulation functions and manage the state of AutoGen processing.

This section describes those functions that are specific to AutoGen. Please take note that these AutoGen specific functions are not loaded and thus not made available until after the command line options have been processed and the AutoGen definitions have been loaded. They may, of course, be used in Scheme functions that get defined at those times, but they cannot be invoked.

> 3.4.1 ``ag-function?'` - test for function |  |
> 3.4.2 ``base-name'` - base output name |  |
> 3.4.3 ``chdir'` - Change current directory |  |
> 3.4.4 ``count'` - definition count |  |
> 3.4.5 ``def-file'` - definitions file name |  |
> 3.4.6 ``dne'` - "Do Not Edit" warning |  |
> 3.4.7 ``error'` - display message and exit |  |
> 3.4.8 ``exist?'` - test for value name |  |
> 3.4.9 ``find-file'` - locate a file in the search path |  |
> 3.4.10 ``first-for?'` - detect first iteration |  |
> 3.4.11 ``for-by'` - set iteration step |  |
> 3.4.12 ``for-from'` - set initial index |  |
> 3.4.13 ``for-index'` - get current loop index |  |
> 3.4.14 ``for-sep'` - set loop separation string |  |
> 3.4.15 ``for-to'` - set ending index |  |
> 3.4.16 ``get'` - get named value |  |
> 3.4.17 ``high-lim'` - get highest value index |  |
> 3.4.18 ``last-for?'` - detect last iteration |  |
> 3.4.19 ``len'` - get count of values |  |
> 3.4.20 ``low-lim'` - get lowest value index |  |
> 3.4.21 ``match-value?'` - test for matching value |  |
> 3.4.22 ``out-delete'` - delete current output file |  |
> 3.4.23 ``out-depth'` - output file stack depth |  |
> 3.4.24 ``out-line'` - output file line number |  |
> 3.4.25 ``out-move'` - change name of output file |  |
> 3.4.26 ``out-name'` - current output file name |  |
> 3.4.27 ``out-pop'` - close current output file |  |
> 3.4.28 ``out-push-add'` - append output to file |  |
> 3.4.29 ``out-push-new'` - purge and create output file |  |
> 3.4.30 ``out-resume'` - resume current output file |  |
> 3.4.31 ``out-suspend'` - suspend current output file |  |
> 3.4.32 ``out-switch'` - close and create new output |  |
> 3.4.33 ``set-option'` - Set a command line option |  |
> 3.4.34 ``set-writable'` - Make the output file be writable |  |
> 3.4.35 ``stack'` - make list of AutoGen values |  |
> 3.4.36 ``suffix'` - get the current suffix |  |
> 3.4.37 ``tpl-file'` - get the template file name |  |
> 3.4.38 ``tpl-file-line'` - get the template file and line number |  |
> 3.4.39 ``make-header-guard'` - make self-inclusion guard |  | ``make-header-guard'` - protect a header file
> 3.4.40 ``autogen-version'` - autogen version number |  | ``autogen-version'` - "5.6.0"

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### 3.4.1 ``ag-function?'` - test for function

Usage: (ag-function? ag-name)
return SCM_BOOL_T if a specified name is a user-defined AutoGen macro, otherwise return SCM_BOOL_F.

Arguments:
ag-name - name of AutoGen macro

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### 3.4.2 ``base-name'` - base output name

Usage: (base-name)
Returns a string containing the base name of the output file(s). Generally, this is also the base name of the definitions file.

This Scheme function takes no arguments.

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### 3.4.3 ``chdir'` - Change current directory

Usage: (chdir dir)
Sets the current directory for AutoGen. Shell commands will run from this directory as well. This is a wrapper around the Guile native function. It returns its directory name argument and fails the program on failure.

Arguments:
dir - new directory name

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### 3.4.4 ``count'` - definition count

Usage: (count ag-name)
Count the number of entries for a definition. The input argument must be a string containing the name of the AutoGen values to be counted. If there is no value associated with the name, the result is an SCM immediate integer value of zero.

Arguments:
ag-name - name of AutoGen value

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### 3.4.5 ``def-file'` - definitions file name

Usage: (def-file)
Get the name of the definitions file. Returns the name of the source file containing the AutoGen definitions.

This Scheme function takes no arguments.

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### 3.4.6 ``dne'` - "Do Not Edit" warning

Usage: (dne prefix [ first_prefix ] [ optpfx ])
Generate a "DO NOT EDIT" or "EDIT WITH CARE" warning string. Which depends on whether or not the `--writable` command line option was set. The first argument is a per-line string prefix. The optional second argument is a prefix for the first-line and, in read-only mode, activates the editor hints.

    -*- buffer-read-only: t -*- vi: set ro:

The warning string also includes information about the template used to construct the file and the definitions used in its instantiation.

The optional third argument is used when the first argument is actually an invocation option and the prefix arguments get shifted. The first argument must be, specifically, "`-d`". That is used to signify that the date stamp should not be inserted into the output.

Arguments:
prefix - string for starting each output line
first_prefix - Optional - for the first output line
optpfx - Optional - shifted prefix

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### 3.4.7 ``error'` - display message and exit

Usage: (error message)
The argument is a string that printed out as part of an error message. The message is formed from the formatting string:

    DEFINITIONS ERROR in %s line %d for %s:  %s\n

The first three arguments to this format are provided by the routine and are: The name of the template file, the line within the template where the error was found, and the current output file name.

After displaying the message, the current output file is removed and autogen exits with the EXIT_FAILURE error code. IF, however, the argument begins with the number 0 (zero), or the string is the empty string, then processing continues with the next suffix.

Arguments:
message - message to display before exiting

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### 3.4.8 ``exist?'` - test for value name

Usage: (exist? ag-name)
return SCM_BOOL_T iff a specified name has an AutoGen value. The name may include indexes and/or member names. All but the last member name must be an aggregate definition. For example:

    (exist? "foo[3].bar.baz")

will yield true if all of the following is true:
There is a member value of either group or string type named `baz` for some group value `bar` that is a member of the `foo` group with index `3`. There may be multiple entries of `bar` within `foo`, only one needs to contain a value for `baz`.

Arguments:
ag-name - name of AutoGen value

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### 3.4.9 ``find-file'` - locate a file in the search path

Usage: (find-file file-name [ suffix ])
AutoGen has a search path that it uses to locate template and definition files. This function will search the same list for ``file-name'`, both with and without the ``.suffix'`, if provided.

Arguments:
file-name - name of file with text
suffix - Optional - file suffix to try, too

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### 3.4.10 ``first-for?'` - detect first iteration

Usage: (first-for? [ for_var ])
Returns SCM_BOOL_T if the named FOR loop (or, if not named, the current innermost loop) is on the first pass through the data. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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### 3.4.11 ``for-by'` - set iteration step

Usage: (for-by by)
This function records the "step by" information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
by - the iteration increment for the AutoGen FOR macro

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### 3.4.12 ``for-from'` - set initial index

Usage: (for-from from)
This function records the initial index information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
from - the initial index for the AutoGen FOR macro

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### 3.4.13 ``for-index'` - get current loop index

Usage: (for-index [ for_var ])
Returns the current index for the named FOR loop. If not named, then the index for the innermost loop. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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### 3.4.14 ``for-sep'` - set loop separation string

Usage: (for-sep separator)
This function records the separation string that is to be inserted between each iteration of an AutoGen FOR function. This is often nothing more than a comma. Outside of the FOR macro itself, this function will emit an error.

Arguments:
separator - the text to insert between the output of each FOR iteration

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### 3.4.15 ``for-to'` - set ending index

Usage: (for-to to)
This function records the terminating value information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
to - the final index for the AutoGen FOR macro

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### 3.4.16 ``get'` - get named value

Usage: (get ag-name [ alt-val ])
Get the first string value associated with the name. It will either return the associated string value (if the name resolves), the alternate value (if one is provided), or else the empty string.

Arguments:
ag-name - name of AutoGen value
alt-val - Optional - value if not present

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### 3.4.17 ``high-lim'` - get highest value index

Usage: (high-lim ag-name)
Returns the highest index associated with an array of definitions. This is generally, but not necessarily, one less than the `count` value. (The indexes may be specified, rendering a non-zero based or sparse array of values.)

This is very useful for specifying the size of a zero-based array of values where not all values are present. For example:

    tMyStruct myVals[ [+ (+ 1 (high-lim "my-val-list")) +] ];

Arguments:
ag-name - name of AutoGen value

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### 3.4.18 ``last-for?'` - detect last iteration

Usage: (last-for? [ for_var ])
Returns SCM_BOOL_T if the named FOR loop (or, if not named, the current innermost loop) is on the last pass through the data. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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### 3.4.19 ``len'` - get count of values

Usage: (len ag-name)
If the named object is a group definition, then "len" is the same as "count". Otherwise, if it is one or more text definitions, then it is the sum of their string lengths. If it is a single text definition, then it is equivalent to `(string-length (get "ag-name"))`.

Arguments:
ag-name - name of AutoGen value

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### 3.4.20 ``low-lim'` - get lowest value index

Usage: (low-lim ag-name)
Returns the lowest index associated with an array of definitions.

Arguments:
ag-name - name of AutoGen value

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### 3.4.21 ``match-value?'` - test for matching value

Usage: (match-value? op ag-name test-str)
This function answers the question, "Is there an AutoGen value named `ag-name` with a value that matches the pattern `test-str` using the match function `op`?" Return SCM_BOOL_T iff at least one occurrence of the specified name has such a value. The operator can be any function that takes two string arguments and yields a boolean. It is expected that you will use one of the string matching functions provided by AutoGen.
The value name must follow the same rules as the `ag-name` argument for `exist?` (see section 3.4.8 ``exist?'` - test for value name).

Arguments:
op - boolean result operator
ag-name - name of AutoGen value
test-str - string to test against

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### 3.4.22 ``out-delete'` - delete current output file

Usage: (out-delete)
Remove the current output file. Cease processing the template for the current suffix. It is an error if there are `push`-ed output files. Use the `(error "0")` scheme function instead. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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### 3.4.23 ``out-depth'` - output file stack depth

Usage: (out-depth)
Returns the depth of the output file stack. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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### 3.4.24 ``out-line'` - output file line number

Usage: (out-line)
Returns the current line number of the output file. It rewinds and reads the file to count newlines.

This Scheme function takes no arguments.

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### 3.4.25 ``out-move'` - change name of output file

Usage: (out-move new-name)
Rename current output file. See section 3.7 Redirecting Output. Please note: changing the name will not save a temporary file from being deleted. It may, however, be used on the root output file.

Arguments:
new-name - new name for the current output file

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### 3.4.26 ``out-name'` - current output file name

Usage: (out-name)
Returns the name of the current output file. If the current file is a temporary, unnamed file, then it will scan up the chain until a real output file name is found. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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### 3.4.27 ``out-pop'` - close current output file

Usage: (out-pop [ disp ])
If there has been a `push` on the output, then close that file and go back to the previously open file. It is an error if there has not been a `push`. See section 3.7 Redirecting Output.

If there is no argument, no further action is taken. Otherwise, the argument should be `#t` and the contents of the file are returned by the function.

Arguments:
disp - Optional - return contents of the file

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### 3.4.28 ``out-push-add'` - append output to file

Usage: (out-push-add file-name)
Identical to `push-new`, except the contents are not purged, but appended to. See section 3.7 Redirecting Output.

Arguments:
file-name - name of the file to append text to

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### 3.4.29 ``out-push-new'` - purge and create output file

Usage: (out-push-new [ file-name ])
Leave the current output file open, but purge and create a new file that will remain open until a `pop` `delete` or `switch` closes it. The file name is optional and, if omitted, the output will be sent to a temporary file that will be deleted when it is closed. See section 3.7 Redirecting Output.

Arguments:
file-name - Optional - name of the file to create

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### 3.4.30 ``out-resume'` - resume current output file

Usage: (out-resume suspName)
If there has been a suspended output, then make that output descriptor current again. That output must have been suspended with the same tag name given to this routine as its argument.

Arguments:
suspName - A name tag for reactivating

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### 3.4.31 ``out-suspend'` - suspend current output file

Usage: (out-suspend suspName)
If there has been a `push` on the output, then set aside the output descriptor for later reactiviation with `(out-resume "xxx")`. The tag name need not reflect the name of the output file. In fact, the output file may be an anonymous temporary file. You may also change the tag every time you suspend output to a file, because the tag names are forgotten as soon as the file has been "resumed".

Arguments:
suspName - A name tag for reactivating

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### 3.4.32 ``out-switch'` - close and create new output

Usage: (out-switch file-name)
Switch output files - close current file and make the current file pointer refer to the new file. This is equivalent to `out-pop` followed by `out-push-new`, except that you may not pop the base level output file, but you may `switch` it. See section 3.7 Redirecting Output.

Arguments:
file-name - name of the file to create

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### 3.4.33 ``set-option'` - Set a command line option

Usage: (set-option opt)
The text argument must be an option name followed by any needed option argument. Returns SCM_UNDEFINED.

Arguments:
opt - AutoGen option name + its argument

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### 3.4.34 ``set-writable'` - Make the output file be writable

Usage: (set-writable [ set? ])
This function will set the current output file to be writable (or not). This is only effective if neither the `--writable` nor `--not-writable` have been specified. This state is reset when the current suffix's output is complete.

Arguments:
set? - Optional - boolean arg, false to make output non-writable

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### 3.4.35 ``stack'` - make list of AutoGen values

Usage: (stack ag-name)
Create a scheme list of all the strings that are associated with a name. They must all be text values or we choke.

Arguments:
ag-name - AutoGen value name

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### 3.4.36 ``suffix'` - get the current suffix

Usage: (suffix)
Returns the current active suffix (see section 3.1 Format of the Pseudo Macro).

This Scheme function takes no arguments.

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### 3.4.37 ``tpl-file'` - get the template file name

Usage: (tpl-file [ full_path ])
Returns the name of the current template file. If `#t` is passed in as an argument, then the template file is hunted for in the template search path. Otherwise, just the unadorned name.

Arguments:
full_path - Optional - include full path to file

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### 3.4.38 ``tpl-file-line'` - get the template file and line number

Usage: (tpl-file-line [ msg-fmt ])
Returns the file and line number of the current template macro using either the default format, "from %s line %d", or else the format you supply. For example, if you want to insert a "C" language file-line directive, you would supply the format "# %2$d %1$s".

Arguments:
msg-fmt - Optional - formatting for line message

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### 3.4.39 ``make-header-guard'` - make self-inclusion guard

Emit a `#ifndef`/`#define` sequence based upon the output file name and the provided prefix. It will also define a scheme variables named, `header-file` and `header-guard`. The `#define` name is composed as follows:

1. The first element is the string argument and a separating underscore.
2. That is followed by the name of the header file with illegal characters mapped to underscores.
3. The end of the name is always, "`_GUARD`".
4. Finally, the entire string is mapped to upper case.

The final `#define` name is stored in an SCM symbol named `header-guard`. Consequently, the concluding `#endif` for the file should read something like:

    #endif /* [+ (. header-guard) +] */

The name of the header file (the current output file) is also stored in an SCM symbol, `header-file`. Therefore, if you are also generating a C file that uses the previously generated header file, you can put this into that generated file:

    #include "[+ (. header-file) +]"

Obviously, if you are going to produce more than one header file from a particular template, you will need to be careful how these SCM symbols get handled.

Arguments:
prefix - first segment of `#define` name

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### 3.4.40 ``autogen-version'` - autogen version number

This is a symbol defining the current AutoGen version number string. It was first defined in AutoGen-5.2.14. It is currently "5.6.0".

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## 3.5 Common Scheme Functions

This section describes a number of general purpose functions that make the kind of string processing that AutoGen does a little easier. Unlike the AutoGen specific functions (see section 3.4 AutoGen Scheme Functions), these functions are available for direct use during definition load time.

> 3.5.1 ``bsd'` - BSD Public License |  |
> 3.5.2 ``c-string'` - emit string for ANSI C |  |
> 3.5.3 ``error-source-line'` - display of file & line |  |
> 3.5.4 ``extract'` - extract text from another file |  |
> 3.5.5 ``format-arg-count'` - count the args to a format |  |
> 3.5.6 ``fprintf'` - format to a file |  |
> 3.5.7 ``gperf'` - perform a perfect hash function |  |
> 3.5.8 ``gpl'` - GNU General Public License |  |
> 3.5.9 ``hide-email'` - convert eaddr to javascript |  |
> 3.5.10 ``in?'` - test for string in list |  |
> 3.5.11 ``join'` - join string list with separator |  |
> 3.5.12 ``kr-string'` - emit string for K&R C |  |
> 3.5.13 ``lgpl'` - GNU Library General Public License |  |
> 3.5.14 ``license'` - an arbitrary license |  |
> 3.5.15 ``make-gperf'` - build a perfect hash function program |  |
> 3.5.16 ``makefile-script'` - create makefile script |  |
> 3.5.17 ``max'` - maximum value in list |  |
> 3.5.18 ``min'` - minimum value in list |  |
> 3.5.19 ``prefix'` - prefix lines with a string |  |
> 3.5.20 ``printf'` - format to stdout |  |
> 3.5.21 ``raw-shell-str'` - single quote shell string |  |
> 3.5.22 ``shell'` - invoke a shell script |  |
> 3.5.23 ``shell-str'` - double quote shell string |  |
> 3.5.24 ``shellf'` - format a string, run shell |  |
> 3.5.25 ``sprintf'` - format a string |  |
> 3.5.26 ``string-capitalize'` - capitalize a new string |  |
> 3.5.27 ``string-capitalize!'` - capitalize a string |  |
> 3.5.28 ``string-contains-eqv?'` - caseless substring |  |
> 3.5.29 ``string-contains?'` - substring match |  |
> 3.5.30 ``string-downcase'` - lower case a new string |  |
> 3.5.31 ``string-downcase!'` - make a string be lower case |  |
> 3.5.32 ``string-end-eqv-match?'` - caseless regex ending |  |
> 3.5.33 ``string-end-match?'` - regex match end |  |
> 3.5.34 ``string-ends-eqv?'` - caseless string ending |  |
> 3.5.35 ``string-ends-with?'` - string ending |  |
> 3.5.36 ``string-equals?'` - string matching |  |
> 3.5.37 ``string-eqv-match?'` - caseless regex match |  |
> 3.5.38 ``string-eqv?'` - caseless string match |  |
> 3.5.39 ``string-has-eqv-match?'` - caseless regex contains |  |
> 3.5.40 ``string-has-match?'` - contained regex match |  |
> 3.5.41 ``string-match?'` - regex match |  |
> 3.5.42 ``string-start-eqv-match?'` - caseless regex start |  |
> 3.5.43 ``string-start-match?'` - regex match start |  |
> 3.5.44 ``string-starts-eqv?'` - caseless string start |  |
> 3.5.45 ``string-starts-with?'` - string starting |  |
> 3.5.46 ``string-substitute'` - multiple global replacements |  |
> 3.5.47 ``string->c-name!'` - map non-name chars to underscore |  |
> 3.5.48 ``string-tr'` - convert characters with new result |  |
> 3.5.49 ``string-tr!'` - convert characters |  |
> 3.5.50 ``string-upcase'` - upper case a new string |  |
> 3.5.51 ``string-upcase!'` - make a string be upper case |  |
> 3.5.52 ``sub-shell-str'` - back quoted (sub-)shell string |  |
> 3.5.53 ``sum'` - sum of values in list |  |
> 3.5.54 ``html-escape-encode'` - escape special chars |  |

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### 3.5.1 ``bsd'` - BSD Public License

Usage: (bsd prog_name owner prefix)
Emit a string that contains the Free BSD Public License. It takes three arguments: `prefix` contains the string to start each output line. `owner` contains the copyright owner. `prog_name` contains the name of the program the copyright is about.

Arguments:
prog_name - name of the program under the BSD
owner - Grantor of the BSD License
prefix - String for starting each output line

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### 3.5.2 ``c-string'` - emit string for ANSI C

Usage: (c-string string)
Reform a string so that, when printed, the C compiler will be able to compile the data and construct a string that contains exactly what the current string contains. Many non-printing characters are replaced with escape sequences. Newlines are replaced with a backslash, an `n`, a closing quote, a newline, seven spaces and another re-opening quote. The compiler will implicitly concatenate them. The reader will see line breaks.

A K&R compiler will choke. Use `kr-string` for that compiler.

Arguments:
string - string to reformat

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### 3.5.3 ``error-source-line'` - display of file & line

Usage: (error-source-line)
This function is only invoked just before Guile displays an error message. It displays the file name and line number that triggered the evaluation error. You should not need to invoke this routine directly. Guile will do it automatically.

This Scheme function takes no arguments.

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### 3.5.4 ``extract'` - extract text from another file

Usage: (extract file-name marker-fmt [ caveat ] [ default ])
This function is used to help construct output files that may contain text that is carried from one version of the output to the next.

The first two arguments are required, the second are optional:

- The `file-name` argument is used to name the file that contains the demarcated text.
- The `marker-fmt` is a formatting string that is used to construct the starting and ending demarcation strings. The sprintf function is given the `marker-fmt` with two arguments. The first is either "START" or "END". The second is either "DO NOT CHANGE THIS COMMENT" or the optional `caveat` argument.
- `caveat` is presumed to be absent if it is the empty string (`""`). If absent, "DO NOT CHANGE THIS COMMENT" is used as the second string argument to the `marker-fmt`.
- When a `default` argument is supplied and no pre-existing text is found, then this text will be inserted between the START and END markers.

The resulting strings are presumed to be unique within the subject file. As a simplified example:

    [+ (extract "fname" "// %s - SOMETHING - %s" ""
    "example default") +]

will result in the following text being inserted into the output:

    // START - SOMETHING - DO NOT CHANGE THIS COMMENT
    example default
    // END   - SOMETHING - DO NOT CHANGE THIS COMMENT

The "`example default`" string can then be carried forward to the next generation of the output, provided the output is not named "`fname`" and the old output is renamed to "`fname`" before AutoGen-eration begins.

NOTE:
  You can set aside previously generated source files inside the pseudo macro with a Guile/scheme function, extract the text you want to keep with this extract function. Just remember you should delete it at the end, too. Here is an example from my Finite State Machine generator:

    [+ AutoGen5 Template  -*- Mode: text -*-
    h=%s-fsm.h   c=%s-fsm.c
    (shellf
    "[ -f %1$s-fsm.h ] && mv -f %1$s-fsm.h .fsm.head
    [ -f %1$s-fsm.c ] && mv -f %1$s-fsm.c .fsm.code" (base-name)) +]

This code will move the two previously produced output files to files named ".fsm.head" and ".fsm.code". At the end of the 'c' output processing, I delete them.

Arguments:
file-name - name of file with text
marker-fmt - format for marker text
caveat - Optional - warn about changing marker
default - Optional - default initial text

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### 3.5.5 ``format-arg-count'` - count the args to a format

Usage: (format-arg-count format)
Sometimes, it is useful to simply be able to figure out how many arguments are required by a format string. For example, if you are extracting a format string for the purpose of generating a macro to invoke a printf-like function, you can run the formatting string through this function to determine how many arguments to provide for in the macro. e.g. for this extraction text:

     /*=fumble bumble
      * fmt: 'stumble %s: %d\n'
     =*/

You may wish to generate a macro:

     #define BUMBLE(a1,a2) printf_like(something,(a1),(a2))

You can do this by knowing that the format needs two arguments.

Arguments:
format - formatting string

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### 3.5.6 ``fprintf'` - format to a file

Usage: (fprintf port format [ format-arg ... ])
Format a string using arguments from the alist. Write to a specified port. The result will NOT appear in your output. Use this to print information messages to a template user.

Arguments:
port - Guile-scheme output port
format - formatting string
format-arg - Optional - list of arguments to formatting string

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### 3.5.7 ``gperf'` - perform a perfect hash function

Usage: (gperf name str)
Perform the perfect hash on the input string. This is only useful if you have previously created a gperf program with the `make-gperf` function See section 3.5.15 ``make-gperf'` - build a perfect hash function program. The `name` you supply here must match the name used to create the program and the string to hash must be one of the strings supplied in the `make-gperf` string list. The result will be a perfect hash index.

See the documentation for `gperf(1GNU)` for more details.

Arguments:
name - name of hash list
str - string to hash

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### 3.5.8 ``gpl'` - GNU General Public License

Usage: (gpl prog-name prefix)
Emit a string that contains the GNU General Public License. It takes two arguments: `prefix` contains the string to start each output line, and `prog_name` contains the name of the program the copyright is about.

Arguments:
prog-name - name of the program under the GPL
prefix - String for starting each output line

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### 3.5.9 ``hide-email'` - convert eaddr to javascript

Usage: (hide-email display eaddr)
Hides an email address as a java scriptlett. The 'mailto:' tag and the email address are coded bytes rather than plain text. They are also broken up.

Arguments:
display - display text
eaddr - email address

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### 3.5.10 ``in?'` - test for string in list

Usage: (in? test-string string-list ...)
Return SCM_BOOL_T if the first argument string is found in one of the entries in the second (list-of-strings) argument.

Arguments:
test-string - string to look for
string-list - list of strings to check

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### 3.5.11 ``join'` - join string list with separator

Usage: (join separator list ...)
With the first argument as the separator string, joins together an a-list of strings into one long string. The list may contain nested lists, partly because you cannot always control that.

Arguments:
separator - string to insert between entries
list - list of strings to join

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### 3.5.12 ``kr-string'` - emit string for K&R C

Usage: (kr-string string)
Reform a string so that, when printed, a K&R C compiler will be able to compile the data and construct a string that contains exactly what the current string contains. Many non-printing characters are replaced with escape sequences. New-lines are replaced with a backslash-n-backslash and newline sequence,

Arguments:
string - string to reformat

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### 3.5.13 ``lgpl'` - GNU Library General Public License

Usage: (lgpl prog_name owner prefix)
Emit a string that contains the GNU Library General Public License. It takes three arguments: `prefix` contains the string to start each output line. `owner` contains the copyright owner. `prog_name` contains the name of the program the copyright is about.

Arguments:
prog_name - name of the program under the LGPL
owner - Grantor of the LGPL
prefix - String for starting each output line

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### 3.5.14 ``license'` - an arbitrary license

Usage: (license lic_name prog_name owner prefix)
Emit a string that contains the named license. The license text is read from a file named, `lic_name`.lic, searching the standard directories. The file contents are used as a format argument to `printf`(3), with `prog_name` and `owner` as the two string formatting arguments. Each output line is automatically prefixed with the string `prefix`.

Arguments:
lic_name - file name of the license
prog_name - name of the licensed program or library
owner - Grantor of the License
prefix - String for starting each output line

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### 3.5.15 ``make-gperf'` - build a perfect hash function program

Usage: (make-gperf name strings ...)
Build a program to perform perfect hashes of a known list of input strings. This function produces no output, but prepares a program named, ``gperf_<name>'` for use by the gperf function See section 3.5.7 ``gperf'` - perform a perfect hash function.

This program will be obliterated within a few seconds after AutoGen exits.

Arguments:
name - name of hash list
strings - list of strings to hash

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### 3.5.16 ``makefile-script'` - create makefile script

Usage: (makefile-script text)
This function will take ordinary shell script text and reformat it so that it will work properly inside of a makefile shell script. Not every shell construct can be supported; the intent is to have most ordinary scripts work without much, if any, alteration.

The following transformations are performed on the source text:

1. Trailing whitespace on each line is stripped.

2. Except for the last line, the string, " ; \\" is appended to the end of every line that does not end with a backslash, semi-colon, conjunction operator or pipe. Note that this will mutilate multi-line quoted strings, but `make` renders it impossible to use multi-line constructs anyway.

3. If the line ends with a backslash, it is left alone.

4. If the line ends with one of the excepted operators, then a space and backslash is added.

5. The dollar sign character is doubled, unless it immediately precedes an opening parenthesis or the single character make macros '*', '<', '@', '?' or '%'. Other single character make macros that do not have enclosing parentheses will fail. For shell usage of the "$@", "$?" and "$*" macros, you must enclose them with curly braces, e.g., "${?}". The ksh construct `$(<command>)` will not work. Though some `make`s accept `${var}` constructs, this function will assume it is for shell interpretation and double the dollar character. You must use `$(var)` for all `make` substitutions.

6. Double dollar signs are replaced by four before the next character is examined.

7. Every line is prefixed with a tab, unless the first line already starts with a tab.

8. The newline character on the last line, if present, is suppressed.

9. Blank lines are stripped.

This function is intended to be used approximately as follows:

    $(TARGET) : $(DEPENDENCIES)
    <+ (out-push-new) +>
    ....mostly arbitrary shell script text....
    <+ (makefile-script (out-pop #t)) +>

Arguments:
text - the text of the script

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### 3.5.17 ``max'` - maximum value in list

Usage: (max list ...)
Return the maximum value in the list

Arguments:
list - list of values. Strings are converted to numbers

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### 3.5.18 ``min'` - minimum value in list

Usage: (min list ...)
Return the minimum value in the list

Arguments:
list - list of values. Strings are converted to numbers

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### 3.5.19 ``prefix'` - prefix lines with a string

Usage: (prefix prefix text)
Prefix every line in the second string with the first string.

For example, if the first string is "# " and the second contains:

    two
    lines

The result string will contain:

    # two
    # lines

Arguments:
prefix - string to insert at start of each line
text - multi-line block of text

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### 3.5.20 ``printf'` - format to stdout

Usage: (printf format [ format-arg ... ])
Format a string using arguments from the alist. Write to the standard out port. The result will NOT appear in your output. Use this to print information messages to a template user. Use "(sprintf ...)" to add text to your document.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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### 3.5.21 ``raw-shell-str'` - single quote shell string

Usage: (raw-shell-str string)
Convert the text of the string into a singly quoted string that a normal shell will process into the original string. (It will not do macro expansion later, either.) Contained single quotes become tripled, with the middle quote escaped with a backslash. Normal shells will reconstitute the original string.

NOTE: some shells will not correctly handle unusual non-printing characters. This routine works for most reasonably conventional ASCII strings.

Arguments:
string - string to transform

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### 3.5.22 ``shell'` - invoke a shell script

Usage: (shell command)
Generate a string by writing the value to a server shell and reading the output back in. The template programmer is responsible for ensuring that it completes within 10 seconds. If it does not, the server will be killed, the output tossed and a new server started.

Arguments:
command - shell command - the result value is stdout

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### 3.5.23 ``shell-str'` - double quote shell string

Usage: (shell-str string)
Convert the text of the string into a double quoted string that a normal shell will process into the original string, almost. It will add the escape character `\\` before two special characters to accomplish this: the backslash `\\` and double quote `"`.

NOTE: some shells will not correctly handle unusual non-printing characters. This routine works for most reasonably conventional ASCII strings.

WARNING:
This function omits the extra backslash in front of a backslash, however, if it is followed by either a backquote or a dollar sign. It must do this because otherwise it would be impossible to protect the dollar sign or backquote from shell evaluation. Consequently, it is not possible to render the strings "\\$" or "\\`". The lesser of two evils.

All others characters are copied directly into the output.

The `sub-shell-str` variation of this routine behaves identically, except that the extra backslash is omitted in front of `"` instead of ```. You have to think about it. I'm open to suggestions.

Meanwhile, the best way to document is with a detailed output example. If the backslashes make it through the text processing correctly, below you will see what happens with three example strings. The first example string contains a list of quoted `foo`s, the second is the same with a single backslash before the quote characters and the last is with two backslash escapes. Below each is the result of the `raw-shell-str`, `shell-str` and `sub-shell-str` functions.

    foo[0]           ''foo'' 'foo' "foo" `foo` $foo
    raw-shell-str -> \'\''foo'\'\'' '\''foo'\'' "foo" `foo` $foo'
    shell-str     -> "''foo'' 'foo' \"foo\" `foo` $foo"
    sub-shell-str -> `''foo'' 'foo' "foo" \`foo\` $foo`

    foo[1]           \'bar\' \"bar\" \`bar\` \$bar
    raw-shell-str -> '\'\''bar\'\'' \"bar\" \`bar\` \$bar'
    shell-str     -> "\\'bar\\' \\\"bar\\\" \`bar\` \$bar"
    sub-shell-str -> `\\'bar\\' \"bar\" \\\`bar\\\` \$bar`

    foo[2]           \\'BAZ\\' \\"BAZ\\" \\`BAZ\\` \\$BAZ
    raw-shell-str -> '\\'\''BAZ\\'\'' \\"BAZ\\" \\`BAZ\\` \\$BAZ'
    shell-str     -> "\\\\'BAZ\\\\' \\\\\"BAZ\\\\\" \\\`BAZ\\\` \\\$BAZ"
    sub-shell-str -> `\\\\'BAZ\\\\' \\\"BAZ\\\" \\\\\`BAZ\\\\\` \\\$BAZ`

There should be four, three, five and three backslashes for the four examples on the last line, respectively. The next to last line should have four, five, three and three backslashes. If this was not accurately reproduced, take a look at the agen5/test/shell.test test. Notice the backslashes in front of the dollar signs. It goes from zero to one to three for the "cooked" string examples.

Arguments:
string - string to transform

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### 3.5.24 ``shellf'` - format a string, run shell

Usage: (shellf format [ format-arg ... ])
Format a string using arguments from the alist, then send the result to the shell for interpretation.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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### 3.5.25 ``sprintf'` - format a string

Usage: (sprintf format [ format-arg ... ])
Format a string using arguments from the alist.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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### 3.5.26 ``string-capitalize'` - capitalize a new string

Usage: (string-capitalize str)
Create a new SCM string containing the same text as the original, only all the first letter of each word is upper cased and all other letters are made lower case.

Arguments:
str - input string

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### 3.5.27 ``string-capitalize!'` - capitalize a string

Usage: (string-capitalize! str)
capitalize all the words in an SCM string.

Arguments:
str - input/output string

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### 3.5.28 ``string-contains-eqv?'` - caseless substring

Usage: (*=* text match)
string-contains-eqv?: Test to see if a string contains an equivalent string. `equivalent' means the strings match, but without regard to character case and certain characters are considered `equivalent'. Viz., '-', '_' and '^' are equivalent.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.29 ``string-contains?'` - substring match

Usage: (*==* text match)
string-contains?: Test to see if a string contains a substring. "strstr(3)" will find an address.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.30 ``string-downcase'` - lower case a new string

Usage: (string-downcase str)
Create a new SCM string containing the same text as the original, only all the upper case letters are changed to lower case.

Arguments:
str - input string

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### 3.5.31 ``string-downcase!'` - make a string be lower case

Usage: (string-downcase! str)
Change to lower case all the characters in an SCM string.

Arguments:
str - input/output string

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### 3.5.32 ``string-end-eqv-match?'` - caseless regex ending

Usage: (*~ text match)
string-end-eqv-match?: Test to see if a string ends with a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.33 ``string-end-match?'` - regex match end

Usage: (*~~ text match)
string-end-match?: Test to see if a string ends with a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.34 ``string-ends-eqv?'` - caseless string ending

Usage: (*= text match)
string-ends-eqv?: Test to see if a string ends with an equivalent string.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.35 ``string-ends-with?'` - string ending

Usage: (*== text match)
string-ends-with?: Test to see if a string ends with a substring. strcmp(3) returns zero for comparing the string ends.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.36 ``string-equals?'` - string matching

Usage: (== text match)
string-equals?: Test to see if two strings exactly match.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.37 ``string-eqv-match?'` - caseless regex match

Usage: (~ text match)
string-eqv-match?: Test to see if a string fully matches a pattern. Case is not significant, but any character equivalences must be expressed in your regular expression.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.38 ``string-eqv?'` - caseless string match

Usage: (= text match)
string-eqv?: Test to see if two strings are equivalent. `equivalent' means the strings match, but without regard to character case and certain characters are considered `equivalent'. Viz., '-', '_' and '^' are equivalent. If the arguments are not strings, then the result of the numeric comparison is returned.

This is an overloaded operation. If the arguments are not both strings, then the query is passed through to `scm_num_eq_p()`.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.39 ``string-has-eqv-match?'` - caseless regex contains

Usage: (*~* text match)
string-has-eqv-match?: Test to see if a string contains a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.40 ``string-has-match?'` - contained regex match

Usage: (*~~* text match)
string-has-match?: Test to see if a string contains a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.41 ``string-match?'` - regex match

Usage: (~~ text match)
string-match?: Test to see if a string fully matches a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.42 ``string-start-eqv-match?'` - caseless regex start

Usage: (~* text match)
string-start-eqv-match?: Test to see if a string starts with a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.43 ``string-start-match?'` - regex match start

Usage: (~~* text match)
string-start-match?: Test to see if a string starts with a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.44 ``string-starts-eqv?'` - caseless string start

Usage: (=* text match)
string-starts-eqv?: Test to see if a string starts with an equivalent string.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.45 ``string-starts-with?'` - string starting

Usage: (==* text match)
string-starts-with?: Test to see if a string starts with a substring.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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### 3.5.46 ``string-substitute'` - multiple global replacements

Usage: (string-substitute source match repl)
`match` and `repl` may be either a single string or a list of strings. Either way, they must have the same structure and number of elements. For example, to replace all less than and all greater than characters, do something like this:

    (string-substitute source
    ("&"     "<"    ">")
    ("&amp;" "<" "&gt;"))

Arguments:
source - string to transform
match - substring or substring list to be replaced
repl - replacement strings or substrings

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### 3.5.47 ``string->c-name!'` - map non-name chars to underscore

Usage: (string->c-name! str)
Change all the graphic characters that are invalid in a C name token into underscores. Whitespace characters are ignored. Any other character type (i.e. non-graphic and non-white) will cause a failure.

Arguments:
str - input/output string

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### 3.5.48 ``string-tr'` - convert characters with new result

Usage: (string-tr source match translation)
This is identical to `string-tr!`, except that it does not over-write the previous value.

Arguments:
source - string to transform
match - characters to be converted
translation - conversion list

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### 3.5.49 ``string-tr!'` - convert characters

Usage: (string-tr! source match translation)
This is the same as the `tr(1)` program, except the string to transform is the first argument. The second and third arguments are used to construct mapping arrays for the transformation of the first argument.

It is too bad this little program has so many different and incompatible implementations!

Arguments:
source - string to transform
match - characters to be converted
translation - conversion list

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### 3.5.50 ``string-upcase'` - upper case a new string

Usage: (string-upcase str)
Create a new SCM string containing the same text as the original, only all the lower case letters are changed to upper case.

Arguments:
str - input string

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### 3.5.51 ``string-upcase!'` - make a string be upper case

Usage: (string-upcase! str)
Change to upper case all the characters in an SCM string.

Arguments:
str - input/output string

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### 3.5.52 ``sub-shell-str'` - back quoted (sub-)shell string

Usage: (sub-shell-str string)
This function is substantially identical to `shell-str`, except that the quoting character is ``` and the "leave the escape alone" character is `"`.

Arguments:
string - string to transform

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### 3.5.53 ``sum'` - sum of values in list

Usage: (sum list ...)
Compute the sum of the list of expressions.

Arguments:
list - list of values. Strings are converted to numbers

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### 3.5.54 ``html-escape-encode'` - escape special chars

Usage: (html-escape-encode str)
Substitute escape sequences for characters that are special to HTML/XML. It will replace "`&`", "`<`" and "`>`" with the strings, "`&`", "`&lt;`", and "`&gt;`", respectively.

Arguments:
str - string to transform

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## 3.6 AutoGen Native Macros

This section describes the various AutoGen natively defined macros. Unlike the Scheme functions, some of these macros are "block macros" with a scope that extends through a terminating macro. Block macros must not overlap. That is to say, a block macro started within the scope of an encompassing block macro must have its matching end macro appear before the encompassing block macro is either ended or subdivided.

The block macros are these:

`CASE`
  This macro has scope through the `ESAC` macro. The scope is subdivided by `SELECT` macros. You must have at least one `SELECT` macro.

`DEFINE`
  This macro has scope through the `ENDDEF` macro. The defined user macro can never be a block macro.

`FOR`
  This macro has scope through the `ENDFOR` macro.

`IF`
  This macro has scope through the `ENDIF` macro. The scope may be subdivided by `ELIF` and `ELSE` macros. Obviously, there may be only one `ELSE` macro and it must be the last of these subdivisions.

`INCLUDE`
  This macro has the scope of the included file. It is a block macro in the sense that the included file must not contain any incomplete block macros.

`WHILE`
  This macro has scope through the `ENDWHILE` macro.

> 3.6.1 AutoGen Macro Syntax |  |
> 3.6.2 CASE - Select one of several template blocks |  |
> 3.6.3 COMMENT - A block of comment to be ignored |  |
> 3.6.4 DEFINE - Define a user AutoGen macro |  |
> 3.6.5 ELIF - Alternate Conditional Template Block |  |
> 3.6.6 ELSE - Alternate Template Block |  |
> 3.6.7 ENDDEF - Ends a macro definition. |  |
> 3.6.8 ENDFOR - Terminates the `FOR` function template block |  |
> 3.6.9 ENDIF - Terminate the `IF` Template Block |  |
> 3.6.10 ENDWHILE - Terminate the `WHILE` Template Block |  |
> 3.6.11 ESAC - Terminate the `CASE` Template Block |  |
> 3.6.12 EXPR - Evaluate and emit an Expression |  |
> 3.6.13 FOR - Emit a template block multiple times |  |
> 3.6.14 IF - Conditionally Emit a Template Block |  |
> 3.6.15 INCLUDE - Read in and emit a template block |  |
> 3.6.16 INVOKE - Invoke a User Defined Macro |  |
> 3.6.17 SELECT - Selection block for CASE function |  |
> 3.6.18 UNKNOWN - Either a user macro or a value name. |  |
> 3.6.19 WHILE - Conditionally loop over a Template Block |  |

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### 3.6.1 AutoGen Macro Syntax

The general syntax is:

    [ { <native-macro-name> | <user-defined-name> } ] [ <arg> ... ]

The syntax for `<arg>` depends on the particular macro, but is generally a full expression (see section 3.3 Macro Expression Syntax). Here are the exceptions to that general rule:

1. `INVOKE` macros, implicit or explicit, must be followed by a list of name/string value pairs. The string values are simple expressions, as described above.

   That is, the `INVOKE` syntax is either:

       <user-macro-name> [ <name> [ = <expression> ] ... ]

   or

       INVOKE <name-expression> [ <name> [ = <expression> ] ... ]

2. AutoGen FOR macros must be in one of two forms:

       FOR <name> [ <separator-string> ]

   or

       FOR <name> (...Scheme expression list)

   where `<name>` must be a simple name and the Scheme expression list is expected to contain one or more of the `for-from`, `for-to`, `for-by`, and `for-sep` functions. (See section 3.6.13 FOR - Emit a template block multiple times, and 3.4 AutoGen Scheme Functions)

3. AutoGen `DEFINE` macros must be followed by a simple name. Anything after that is ignored. See section 3.6.4 DEFINE - Define a user AutoGen macro.

4. The AutoGen `COMMENT`, `ELSE`, `ESAC` and the `END*` macros take no arguments and ignore everything after the macro name (e.g. see 3.6.3 COMMENT - A block of comment to be ignored)

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### 3.6.2 CASE - Select one of several template blocks

The arguments are evaluated and converted to a string, if necessary. (see section 3.6.12 EXPR - Evaluate and emit an Expression) The scope of the macro is up to the matching ESAC function. Within the scope of a CASE, this string is matched against case selection macros. There are sixteen match macros that are derived from four different ways the test may be performed, plus an "always true" match. The code for each selection expression is formed as follows:

1. Must the match start matching from the beginning of the string? If not, then the match macro code starts with an asterisk (`*`).
2. Must the match finish matching at the end of the string? If not, then the match macro code ends with an asterisk (`*`).
3. Is the match a pattern match or a string comparison? If a comparison, use an equal sign (`=`). If a pattern match, use a tilde (`~`).
4. Is the match case sensitive? If alphabetic case is important, double the tilde or equal sign.
5. Do you need a default match when none of the others match? Use a single asterisk (`*`).

For example:

    [+ CASE <full-expression> +]
    [+ ~~*  "[Tt]est" +]reg exp must match at start, not at end
    [+ ==   "TeSt"    +]a full-string, case sensitive compare
    [+ =    "TEST"    +]a full-string, case insensitive compare
    [+ *              +]always match - no testing
    [+ ESAC +]

`<full-expression>` (see section 3.3 Macro Expression Syntax) may be any expression, including the use of apply-codes and value-names. If the expression yields a number, it is converted to a decimal string.

These case selection codes have also been implemented as Scheme expression functions using the same codes (see section 3.5 Common Scheme Functions).

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### 3.6.3 COMMENT - A block of comment to be ignored

This function can be specified by the user, but there will never be a situation where it will be invoked at emit time. The macro is actually removed from the internal representation.

If the native macro name code is `#`, then the entire macro function is treated as a comment and ignored.

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### 3.6.4 DEFINE - Define a user AutoGen macro

This function will define a new macro. You must provide a name for the macro. You do not specify any arguments, though the invocation may specify a set of name/value pairs that are to be active during the processing of the macro.

    [+ define foo +]
    ... macro body with macro functions ...
    [+ enddef +]
    ... [+ foo bar='raw text' baz=<<text expression>> +]

Once the macro has been defined, this new macro can be invoked by specifying the macro name as the first token after the start macro marker. Alternatively, you may make the invocation explicitly invoke a defined macro by specifying `INVOKE` in the macro invocation. If you do that, the macro name can be computed with an expression that gets evaluated every time the INVOKE macro is encountered. See section 3.6.16 INVOKE - Invoke a User Defined Macro.

Any remaining text in the macro invocation will be used to create new name/value pairs that only persist for the duration of the processing of the macro. The expressions are evaluated the same way basic expressions are evaluated. See section 3.3 Macro Expression Syntax.

The resulting definitions are handled much like regular definitions, except:

1. The values may not be compound. That is, they may not contain nested name/value pairs.
2. The bindings go away when the macro is complete.
3. The name/value pairs are separated by whitespace instead of semi-colons.
4. Sequences of strings are not concatenated.

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### 3.6.5 ELIF - Alternate Conditional Template Block

This macro must only appear after an `IF` function, and before any associated `ELSE` or `ENDIF` functions. It denotes the start of an alternate template block for the `IF` function. Its expression argument is evaluated as are the arguments to `IF`. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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### 3.6.6 ELSE - Alternate Template Block

This macro must only appear after an `IF` function, and before the associated `ENDIF` function. It denotes the start of an alternate template block for the `IF` function. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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### 3.6.7 ENDDEF - Ends a macro definition.

This macro ends the `DEFINE` function template block. For a complete description See section 3.6.4 DEFINE - Define a user AutoGen macro.

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### 3.6.8 ENDFOR - Terminates the `FOR` function template block

This macro ends the `FOR` function template block. For a complete description See section 3.6.13 FOR - Emit a template block multiple times.

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### 3.6.9 ENDIF - Terminate the `IF` Template Block

This macro ends the `IF` function template block. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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### 3.6.10 ENDWHILE - Terminate the `WHILE` Template Block

This macro ends the `WHILE` function template block. For a complete description See section 3.6.19 WHILE - Conditionally loop over a Template Block.

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### 3.6.11 ESAC - Terminate the `CASE` Template Block

This macro ends the `CASE` function template block. For a complete description, See section 3.6.2 CASE - Select one of several template blocks.

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### 3.6.12 EXPR - Evaluate and emit an Expression

This macro does not have a name to cause it to be invoked explicitly, though if a macro starts with one of the apply codes or one of the simple expression markers, then an expression macro is inferred. The result of the expression evaluation (see section 3.3 Macro Expression Syntax) is written to the current output.

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### 3.6.13 FOR - Emit a template block multiple times

This macro has a slight variation on the standard syntax:

    FOR <value-name> [ <separator-string> ]

or

    FOR <value-name> (...Scheme expression list

or

    FOR <value-name> IN "quoted string" unquoted-string ...

Other than for the last form, the first macro argument must be the name of an AutoGen value. If there is no value associated with the name, the `FOR` template block is skipped entirely. The scope of the `FOR` macro extends to the corresponding `ENDFOR` macro. The last form will create an array of string values named `<value-name>` that only exists within the context of this `FOR` loop. With this form, in order to use a `separator-string`, you must code it into the end of the template block using the `(last-for?)` predicate function (see section 3.4.18 ``last-for?'` - detect last iteration).

If there are any arguments after the `value-name`, the initial characters are used to determine the form. If the first character is either a semi-colon (`;`) or an opening parenthesis (`(`), then it is presumed to be a Scheme expression containing the FOR macro specific functions `for-from`, `for-by`, `for-to`, and/or `for-sep`. See section 3.4 AutoGen Scheme Functions. If it consists of an '`i`' an '`n`' and separated by white space from more text, then the `FOR x IN` form is processed. Otherwise, the remaining text is presumed to be a string for inserting between each iteration of the loop. This string will be emitted one time less than the number of iterations of the loop. That is, it is emitted after each loop, excepting for the last iteration.

If the from/by/to functions are invoked, they will specify which copies of the named value are to be processed. If there is no copy of the named value associated with a particular index, the `FOR` template block will be instantiated anyway. The template must use methods for detecting missing definitions and emitting default text. In this fashion, you can insert entries from a sparse or non-zero based array into a dense, zero based array.

NB: the `for-from`, `for-to`, `for-by` and `for-sep` functions are disabled outside of the context of the `FOR` macro. Likewise, the `first-for`, `last-for` and `for-index` functions are disabled outside of the range of a `FOR` block.

    [+FOR var (for-from 0) (for-to <number>) (for-sep ",") +]
    ... text with various substitutions ...[+
    ENDFOR var+]

this will repeat the `... text with `var`ious substitutions ...` <number>+1 times. Each repetition, except for the last, will have a comma `,` after it.

    [+FOR var ",\n" +]
    ... text with various substitutions ...[+
    ENDFOR var +]

This will do the same thing, but only for the index values of `var` that have actually been defined.

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### 3.6.14 IF - Conditionally Emit a Template Block

Conditional block. Its arguments are evaluated (see section 3.6.12 EXPR - Evaluate and emit an Expression) and if the result is non-zero or a string with one or more bytes, then the condition is true and the text from that point until a matched `ELIF`, `ELSE` or `ENDIF` is emitted. `ELIF` introduces a conditional alternative if the `IF` clause evaluated FALSE and `ELSE` introduces an unconditional alternative.

    [+IF <full-expression> +]
    emit things that are for the true condition[+

    ELIF <full-expression-2> +]
    emit things that are true maybe[+

    ELSE "This may be a comment" +]
    emit this if all but else fails[+

    ENDIF "This may *also* be a comment" +]

`<full-expression>` may be any expression described in the `EXPR` expression function, including the use of apply-codes and value-names. If the expression yields an empty string, it is interpreted as false.

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### 3.6.15 INCLUDE - Read in and emit a template block

The entire contents of the named file is inserted at this point. The contents of the file are processed for macro expansion. The arguments are eval-ed, so you may compute the name of the file to be included. The included file must not contain any incomplete function blocks. Function blocks are template text beginning with any of the macro functions ``CASE'`, ``DEFINE'`, ``FOR'`, ``IF'` and ``WHILE'`; extending through their respective terminating macro functions.

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### 3.6.16 INVOKE - Invoke a User Defined Macro

User defined macros may be invoked explicitly or implicitly. If you invoke one implicitly, the macro must begin with the name of the defined macro. Consequently, this may not be a computed value. If you explicitly invoke a user defined macro, the macro begins with the macro name `INVOKE` followed by a basic expression that must yield a known user defined macro. A macro name _must_ be found, or AutoGen will issue a diagnostic and exit.

Arguments are passed to the invoked macro by name. The text following the macro name must consist of a series of names each of which is followed by an equal sign (`=`) and a basic expression that yields a string.

The string values may contain template macros that are parsed the first time the macro is processed and evaluated again every time the macro is evaluated.

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### 3.6.17 SELECT - Selection block for CASE function

This macro selects a block of text by matching an expression against the sample text expression evaluated in the `CASE` macro. See section 3.6.2 CASE - Select one of several template blocks.

You do not specify a `SELECT` macro with the word "select". Instead, you must use one of the 17 match operators described in the `CASE` macro description.

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### 3.6.18 UNKNOWN - Either a user macro or a value name.

The macro text has started with a name not known to AutoGen. If, at run time, it turns out to be the name of a defined macro, then that macro is invoked. If it is not, then it is a conditional expression that is evaluated only if the name is defined at the time the macro is invoked.

You may not specify `UNKNOWN` explicitly.

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### 3.6.19 WHILE - Conditionally loop over a Template Block

Conditionally repeated block. Its arguments are evaluated (see section 3.6.12 EXPR - Evaluate and emit an Expression) and as long as the result is non-zero or a string with one or more bytes, then the condition is true and the text from that point until a matched `ENDWHILE` is emitted.

    [+WHILE <full-expression> +]
    emit things that are for the true condition[+

    ENDWHILE +]

`<full-expression>` may be any expression described in the `EXPR` expression function, including the use of apply-codes and value-names. If the expression yields an empty string, it is interpreted as false.

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## 3.7 Redirecting Output

AutoGen provides a means for redirecting the template output to different files or, in ``M4'` parlance, to various diversions. It is accomplished by providing a set of Scheme functions named `out-*` (see section 3.4 AutoGen Scheme Functions).

``out-push-new (see section 3.4.29 ``out-push-new'` - purge and create output file)'`
  This allows you to logically "push" output files onto a stack. If you supply a string name, then a file by that name is created to hold the output. If you do not supply a name, then the text is written to a scratchpad and retrieved by passing a "`#t`" argument to the `out-pop` (see section 3.4.27 ``out-pop'` - close current output file) function.

``out-pop (see section 3.4.27 ``out-pop'` - close current output file)'`
  This function closes the current output file and resumes output to the next one in the stack. At least one output must have been pushed onto the output stack with the `out-push-new` (see section 3.4.29 ``out-push-new'` - purge and create output file) function. If "`#t`" is passed in as an argument, then the entire contents of the diversion (or file) is returned.

``out-suspend (see section 3.4.31 ``out-suspend'` - suspend current output file)'`
  This function does not close the current output, but instead sets it aside for resumption by the given name with `out-resume`. The current output must have been pushed on the output queue with `out-push-new` (see section 3.4.29 ``out-push-new'` - purge and create output file).

``out-resume (see section 3.4.30 ``out-resume'` - resume current output file)'`
  This will put a named file descriptor back onto the top of stack so that it becomes the current output again.

``out-switch (see section 3.4.32 ``out-switch'` - close and create new output)'`
  This closes the current output and creates a new file, purging any preexisting one. This is a shortcut for "pop" followed by "push", but this can also be done at the base level.

``out-move (see section 3.4.25 ``out-move'` - change name of output file)'`
  Renames the current output file without closing it.

There are also several functions for determining the output status. See section 3.4 AutoGen Scheme Functions.

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This document was generated by Bruce Korb on February 23, 2004 using texi2html