Provided by: libsyntax-highlight-perl-perl_1.00-2_all 
NAME
Syntax::Highlight::Perl - Highlighting of Perl Syntactical Structures
VERSION
This file documents Syntax::Highlight::Perl version 1.0.
SYNOPSIS
# simple procedural
use Syntax::Highlight::Perl ':BASIC'; # or ':FULL'
print format_string($my_string);
# OO
use Syntax::Highlight::Perl;
my $formatter = new Syntax::Highlight::Perl;
print $formatter->format_string($my_string);
DESCRIPTION
This module provides syntax highlighting for Perl code. The design bias is roughly line-oriented and
streamed (ie, processing a file line-by-line in a single pass). Provisions may be made in the future for
tasks related to "back-tracking" (ie, re-doing a single line in the middle of a stream) such as speeding
up state copying.
Constructors
The only constructor provided is "new()". When called on an existing object, "new()" will create a new
copy of that object. Otherwise, "new()" creates a new copy of the (internal) Default Object. Note that
the use of the procedural syntax modifies the Default Object and that those changes will be reflected in
any subsequent "new()" calls.
Formatting
Formatting is done using the "format_string()" method. Call "format_string()" with one or more strings
to format, or it will default to using $_.
Setting and Getting Formats
You can set the text used for formatting a syntax element using "set_format()" (or set the start and end
format individually using "set_start_format()" and "set_end_format()", respectively).
You can also retrieve the text used for formatting for an element via "get_start_format()" or
"get_end_format". Bulk retrieval of the names or values of defined formats is possible via
"get_format_names_list()" (names), "get_start_format_values_list()" and "get_end_format_values_list()".
See "FORMAT TYPES" later in this document for information on what format elements can be used.
Checking and Setting the State
You can check certain aspects of the state of the formatter via the methods: "in_heredoc()",
"in_string()", "in_pod()", "was_pod()", "in_data()", and "line_count()".
You can reset all of the above states (and a few other internal ones) using "reset()".
Stable and Unstable Formatting Modes
You can set or check the stability of formatting via "unstable()".
In unstable (TRUE) mode, formatting is not considered to be persistent with nested formats. Or, put
another way, when unstable, the formatter can only "remember" one format at a time and must reinstate
formatting for each token. An example of unstable formatting is using ANSI color escape sequences in a
terminal.
In stable (FALSE) mode (the default), formatting is considered persistent within arbitrarily nested
formats. Even in stable mode, however, formatting is never allowed to span multiple lines; it is always
fully closed at the end of the line and reinstated at the beginning of a new line, if necessary. This is
to ensure properly balanced tags when only formatting a partial code snippet. An example of stable
formatting is HTML.
Substitutions
Using "define_substitution()", you can have the formatter substitute certain strings with others, after
the original string has been parsed (but before formatting is applied). This is useful for escaping
characters special to the output mode (eg, > and < in HTML) without them affecting the way the code is
parsed.
You can retrieve the current substitutions (as a hash-ref) via "substitutions()".
FORMAT TYPES
The Syntax::Highlight::Perl formatter recognizes and differentiates between many Perl syntactical
elements. Each type of syntactical element has a Format Type associated with it. There is also a
'DEFAULT' type that is applied to any element who's Format Type does not have a value.
Several of the Format Types have underscores in their name. This underscore is special, and indicates
that the Format Type can be "generalized." This means that you can assign a value to just the first part
of the Format Type name (the part before the underscore) and that value will be applied to all Format
Types with the same first part. For example, the Format Types for all types of variables begin with
"Variable_". Thus, if you assign a value to the Format Type "Variable", it will be applied to any type
of variable. Generalized Format Types take precedence over non-generalized Format Types. So the value
assigned to "Variable" would be applied to "Variable_Scalar", even if "Variable_Scalar" had a value
explicitly assigned to it.
You can also define a "short-cut" name for each Format Type that can be generalized. The short-cut name
would be the part of the Format Type name after the underscore. For example, the short-cut for
"Variable_Scalar" would be "Scalar". Short-cut names have the least precedence and are only assigned if
neither the generalized Type name, nor the full Type name have values.
Following is a list of all the syntactical elements that Syntax::Highlight::Perl currently recognizes,
along with a short description of what each would be applied to.
Comment_Normal
A normal Perl comment. Starts with '#' and goes until the end of the line.
Comment_POD
Inline documentation. Starts with a line beginning with an equal sign ('=') followed by a word (eg:
'=pod') and continuing until a line beginning with '=cut'.
Directive
Either the "she-bang" line at the beginning of the file, or a line directive altering what the
compiler thinks the current line and file is.
Label
A loop or statement label (to be the target of a goto, next, last or redo).
Quote
Any string or character that begins or ends a String. Including, but not necessarily limited to:
quote-like regular expression operators ("m//", "s///", "tr///", etc), a Here-Document terminating
line, the lone period terminating a format, and, of course, normal quotes ("'", """, "`", "q{}",
"qq{}", "qr{}", "qx{}").
String
Any text within quotes, "format"s, Here-Documents, Regular Expressions, and the like.
Subroutine
The identifier used to define, identify, or call a subroutine (or method). Note that
Syntax::Highlight::Perl cannot recognize a subroutine if it is called without using parentheses or an
ampersand, or methods called using the indirect object syntax. It formats those as barewords.
Variable_Scalar
A scalar variable.
Note that (theoretically) this format is not applied to non-scalar variables that are being used as
scalars (ie: array or hash lookups, nor references to anything other than scalars).
Syntax::Highlight::Perl figures out (or at least tries to) the actual type of the variable being used
(by looking at how you're subscripting it) and formats it accordingly. The first character of the
variable (ie, the "$", "@", "%", or "*") tells you the type of value being used, and the color
(hopefully) tells you the type of variable being used to get that value.
(See "KNOWN ISSUES" for information about when this doesn't work quite right.)
Variable_Array
An array variable (but not usually a slice; see above).
Variable_Hash
A hash variable.
Variable_Typeglob
A typeglob. Note that typeglobs not beginning with an asterisk (*) (eg: filehandles) are formatted
as barewords. This is because, well, they are.
Whitespace
Whitespace. Not usually formatted but it can be.
Character
A special, or backslash-escaped, character. For example: "\n" (newline), or "\d" (digits).
Only occurs within strings or regular expressions.
Keyword
A Perl keyword. Some examples include: my, local, sub, next.
Note that Perl does not make any distinction between keywords and built-in functions (at least not in
the documentation). Thus I had to make a subjective call as to what would be considered keywords and
what would be built-in functions.
The list of keywords can be found (and overloaded) in the variable
$Syntax::Highlight::Perl::keyword_list_re as a pre-compiled regular expression.
Builtin_Function
A Perl built-in function, called as a function (ie, using parentheses).
The list of built-in functions can be found (and overloaded) in the variable
$Syntax::Highlight::Perl::builtin_list_re as a pre-compiled regular expression.
Builtin_Operator
A Perl built-in function, called as a list or unary operator (ie, without using parentheses).
The list of built-in functions can be found (and overloaded) in the variable
$Syntax::Highlight::Perl::builtin_list_re as a pre-compiled regular expression.
Operator
A Perl operator.
The list of operators can be found (and overloaded) in the variable
$Syntax::Highlight::Perl::operator_list_re as a pre-compiled regular expression.
Bareword
A bareword. This can be user-defined subroutine called without parentheses, a typeglob used without
an asterisk (*), or just a plain old bareword.
Package
The name of a package or pragmatic module.
Note that this does not apply to the package portion of a fully qualified variable name.
Number
A numeric literal.
Symbol
A symbol (ie, non-operator punctuation).
CodeTerm
The special tokens that signal the end of executable code and the begining of the DATA section.
Specifically, '"__END__"' and '"__DATA__"'.
DATA
Anything in the DATA section (see "CodeTerm").
PROCEDURAL vs. OBJECT ORIENTED
Syntax::Highlight::Perl uses OO method-calls internally (and actually defines a Default Object that is
used when the functions are invoked procedurally) so you will not gain anything (efficiency-wise) by
using the procedural interface. It is just a matter of style.
It is actually recommended that you use the OO interface, as this allows you to instantiate multiple,
concurrent-yet-separate formatters. Though I cannot think of why you would need multiple formatters
instantiated. :-)
One point to note: the "new()" method uses the Default Object to initialize new objects. This means that
any changes to the state of the Default Object (including Format definitions) made by using the
procedural interface will be reflected in any subsequently created objects. This can be useful in some
cases (eg, call "set_format()" procedurally just before creating a batch of new objects to define default
Formats for them all) but will most likely lead to trouble.
METHODS
new PACKAGE
new OBJECT
Creates a new object. If called on an existing object, creates a new copy of that object (which is
thenceforth totally separate from the original).
reset
Resets the object's internal state. This breaks out of strings and here-docs, ends PODs, resets the
line-count, and otherwise gets the object back into a "normal" state to begin processing a new
stream.
Note that this does not reset any user options (including formats and format stability).
unstable EXPR
unstable
Returns true if the formatter is in unstable mode.
If called with a non-zero number, puts the formatter into unstable formatting mode.
In unstable mode, it is assumed that formatting is not persistent one token to the next and that each
token must be explicitly formatted.
in_heredoc
Returns true if the next string to be formatted will be inside a Here-Document.
in_string
Returns true if the next string to be formatted will be inside a multi-line string.
in_pod
Returns true if the formatter would consider the next string passed to it as begin within a POD
structure. This is false immediately before any POD instigators ("=pod", "=head1", "=item", etc),
true immediately after an instigator, throughout the POD and immediately before the POD terminator
("=cut"), and false immediately after the POD terminator.
was_pod
Returns true if the last line of the string just formatted was part of a POD structure. This
includes the "/^=\w+/" POD instigators and terminators.
in_data
Returns true if the next string to be formatted will be inside the DATA section (ie, follows a
"__DATA__" or "__END__" tag).
line_count
Returns the number of lines processed by the formatter.
substitutions
Returns a reference to the substitution table used. The substitution table is a hash whose keys are
the strings to be replaced, and whose values are what to replace them with.
define_substitution HASH_REF
define_substitution LIST
Allows user to define certain characters that will be substituted before formatting is done (but
after they have been processed for meaning).
If the first parameter is a reference to a hash, the formatter will replace it's own hash with the
given one, and subsequent changes to the hash outside the formatter will be reflected.
Otherwise, it will copy the arguments passed into it's own hash, and any substitutions already
defined (but not in the parameter list) will be preserved. (ie, the new substitutions will be added,
without destroying what was there already.)
set_start_format HASH_REF
set_start_format LIST
Given either a list of keys/values, or a reference to a hash of keys/values, copy them into the
object's Formats list.
set_end_format HASH_REF
set_end_format LIST
Given either a list of keys/values, or a reference to a hash of keys/values, copy them into the
object's Formats list.
set_format LIST
Sets the formatting string for one or more formats.
You should pass a list of keys/values where the keys are the format names and the values are
references to arrays containing the starting and ending formatting strings (in that order) for that
format.
get_start_format LIST
Retrieve the string that is inserted to begin a given format type (starting format string).
The names are looked for in the following order:
First: Prefer the names joined by underscore, from most general to least. For example, given
("Variable", "Scalar"): "Variable" then "Variable_Scalar".
Second: Then try each name singly, in reverse order. For example, "Scalar" then "Variable".
See "FORMAT TYPES" for more information.
get_end_format LIST
Retrieve the string that is inserted to end a given format type (ending format string).
get_format_names_list
Returns a list of the names of all the Formats defined.
get_start_format_values_list
Returns a list of the values of all the start Formats defined (in the same order as the names
returned by "get_format_names_list()").
get_end_format_values_list
Returns a list of the values of all the end Formats defined (in the same order as the names returned
by "get_format_names_list()").
format_string LIST
Formats one or more strings of Perl code. If no strings are specified, defaults to $_. Returns the
list of formatted strings (or the first string formatted if called in scalar context).
Note: The end of the string is considered to be the end of a line, regardless of whether or not
there is a trailing line-break (but trailing line-breaks will not cause an extra, empty line).
Another Note: The function actually uses $/ to determine line-breaks, unless $/ is set to "\n"
(newline). If $/ is "\n", then it looks for the first match of "m/\r?\n|\n?\r/" in the string and
uses that to determine line-breaks. This is to make it easy to handle non-unix text. Whatever
characters it ends up using as line-breaks are preserved.
format_token TOKEN, LIST
Returns TOKEN wrapped in the start and end Formats corresponding to LIST (as would be returned by
"get_start_format( LIST )" and "get_end_format( LIST )", respectively).
No syntax checking is done on TOKEN but substitutions defined with "define_substitution()" are
performed.
KNOWN ISSUES or LIMITATIONS
• Barewords used as keys to a hash are formatted as strings. This is Good. They should not be,
however, if they are not the only thing within the curly braces. That can be fixed.
• This version does not handle formats (see perlform(1)) very well. It treats them as Here-Documents
and ignores the rules for comment lines, as well as the fact that picture lines are not supposed to
be interpolated. Thus, your picture lines will look strange with the '@'s being formatted as array
variables (albeit, invalid ones). Ideally, it would also treat value lines as normal Perl code and
format accordingly. I think I'll get to the comment lines and non-interpolating picture lines first.
If/When I do get this fixed, I will most likely add a format type of 'Format' or something, so that
they can be formatted differently, if so desired.
• This version does not handle Regular Expression significant characters. It simply treats Regular
Expressions as interpolated strings.
• User-defined subroutines, called without parentheses, are formatted as barewords. This is because
there is no way to tell them apart from barewords without parsing the code, and would require us to
go as far as perl does when doing the "-c" check (ie, executing BEGIN and END blocks and the like).
That's not going to happen.
• If you are indexing (subscripting) an array or hash, the formatter tries to figure out the "real"
variable class by looking at how you index the variable. However, if you do something funky (but
legal in Perl) and put line-breaks or comments between the variable class character ($) and your
identifier, the formatter will get confused and treat your variable as a scalar. Until it finds the
index character. Then it will format the scalar class character ($) as a scalar and your identifier
as the "correct" class.
• If you put a line-break between your variable identifier and it's indexing character (see above),
which is also legal in Perl, the formatter will never find it and treat your variable as a scalar.
• If you put a line-break between a bareword hash-subscript and the hash variable, or between a
bareword and its associated "=>" operator, the bareword will not be formatted correctly (as a
string). (Noticing a pattern here?)
AUTHOR
Cory Johns darkness@yossman.net
Copyright (c) 2001 Cory Johns. This library is free software; you can redistribute and/or modify it
under the same conditions as Perl itself.
TO DO
1. Improve handling of regular expressions. Add support for regexp-special characters. Recognize the
/e option to the substitution operator (maybe).
2. Improve handling of formats. Don't treat format definitions as interpolating. Handle format-
comments. Possibly format value lines as normal Perl code.
3. Create in-memory deep-copy routine to replace "eval(Data::Dumper)" deep-copy.
4. Generalize state transitions ("reset()" and, in the future, "copy_state()") to use non-hard-coded
keys and values for state variables. Probably will extrapolate them into an overloadable hash, and
use the aforementioned deep-copy to assign them.
5. Create a method to save or copy states between objects ("copy_state()"). Would be useful for using
this module in an editor.
6. Add support for greater-than-one length special characters. Specifically, octal, hexidecimal, and
control character codes. For example, "\644", "\x1a4" or "\c[".
REVISIONS
04-04-2001 Cory Johns
• Fixed problem with special characters not formatting inside of Here-Documents.
• Fixed bug causing hash variables to format inside of Here-Documents.
03-30-2001 Cory Johns
• Fixed bug where quote-terminators were checked for inside of Here-Documents.
03-29-2001 Cory Johns
• Moved token processing tests from _format_line() into _process_token() (where they should've been all
along), generally making _format_line() more logical. Contemplating extrapolating the tokenizing and
token loop into its own subroutine to avoid all the recursive calls.
• Fixed bug that caused special characters to be recognized outside of strings.
• Added $VERSION variable.
• Added support for different types of literal numbers: floating point, exponential notation (eg:
1.3e10), hexidecimal, and underscore-separated.
• Added the "CodeTerm" and "DATA" Formats.
03-27-2001 Cory Johns
• Added was_pod() and updated the documentation for in_pod().
03-20-2001 Cory Johns
• Added support for Perl formats (ie, `"format = ..."').
perl v5.36.0 2023-01-03 Syntax::Highlight::Perl(3pm)