NAME

       HTML::Mason::Compiler - Compile Mason component source

SYNOPSIS

         package My::Funky::Compiler;

         use base qw(HTML::Mason::Compiler);

DESCRIPTION

       The compiler starts the compilation process by calling its lexer's "lex" method and
       passing itself as the "compiler" parameter.  The lexer then calls various methods in the
       compiler as it parses the component source.

PARAMETERS TO THE new() CONSTRUCTOR

       allow_globals
           List of variable names, complete with prefix ("$@%"), that you intend to use as
           globals in components.  Normally global variables are forbidden by "strict", but any
           variable mentioned in this list is granted a reprieve via a "use vars" statement. For
           example:

               allow_globals => [qw($DBH %session)]

           In a mod_perl environment, $r (the request object) is automatically added to this
           list.

       default_escape_flags
           Escape flags to apply to all <% %> expressions by default. The current valid flags are

               h - escape for HTML ('<' => '&lt;', etc.)
               u - escape for URL (':' => '%3A', etc.)

           The developer can override default escape flags on a per-expression basis; see the
           escaping expressions section of the developer's manual.

           If you want to set multiple flags as the default, this should be given as a reference
           to an array of flags.

       enable_autoflush
           True or false, default is true. Indicates whether components are compiled with support
           for autoflush. The component can be compiled to a more efficient form if it does not
           have to check for autoflush mode, so you should set this to 0 if you can.

       lexer
           The Lexer object to associate with this Compiler. By default a new object of class
           lexer_class will be created.

       lexer_class
           The class to use when creating a lexer. Defaults to HTML::Mason::Lexer.

       preprocess
           Sub reference that is called to preprocess each component before the compiler does
           it's magic.  The sub is called with a single parameter, a scalar reference to the
           script.  The sub is expected to process the script in-place.   This is one way to
           extend the HTML::Mason syntax with new tags, etc., although a much more flexible way
           is to subclass the Lexer or Compiler class. See also postprocess_text and
           postprocess_perl.

       postprocess_text
           Sub reference that is called to postprocess the text portion of a compiled component,
           just before it is assembled into its final subroutine form.  The sub is called with a
           single parameter, a scalar reference to the text portion of the component.  The sub is
           expected to process the string in-place. See also preprocess and postprocess_perl.

       postprocess_perl
           Sub reference that is called to postprocess the Perl portion of a compiled component,
           just before it is assembled into its final subroutine form.  The sub is called with a
           single parameter, a scalar reference to the Perl portion of the component.  The sub is
           expected to process the string in-place. See also preprocess and postprocess_text.

       use_source_line_numbers
           True or false, default is true. Indicates whether component line numbers that appear
           in error messages, stack traces, etc. are in terms of the source file instead of the
           object file. Mason does this by inserting '#line' directives into compiled components.
           While source line numbers are more immediately helpful, object file line numbers may
           be more appropriate for in-depth debugging sessions.

ACCESSOR METHODS

       All of the above properties have read-only accessor methods of the same name.

       You cannot change any property of a compiler after it has been created - among other
       things, this would potentially invalidate any existing cached component objects or object
       files. Your best bet is to create different compiler objects and load them into different
       interpreters.

METHODS

       There are several methods besides the compilation callbacks below that a Compiler subclass
       needs to implement.

       compile(...)
           This method has several parameters:

           •       comp_source (required)

                   Either a scalar or reference to a scalar containing the component source.

           •       name (required)

                   The name of the component. This should be the filename of the component if it
                   is file-based, or some other clear identifier of the component source.

           •       comp_path (required)

                   This should be the component's path.

           •       fh (optional)

                   If this is given then the output of the compiler will be sent directly to this
                   handle, rather than being buffered in memory. This is an optimization to avoid
                   memory usage.

       object_id
           This method should return a unique id for the given compiler object.  This is used by
           the interpreter when determining the object directory, for example.

   Compilation Callbacks
       These are methods called by the Lexer while processing a component source.  You may wish
       to override some of these methods if you're implementing your own custom Compiler class.

       start_component()
           This method is called by the Lexer when it starts processing a component.

       end_component()
           This method is called by the Lexer when it finishes processing a component.

       start_block(block_type => <string>)
           This method is called by the Lexer when it encounters an opening Mason block tag like
           "<%perl>" or "<%args>".  Its main purpose is to keep track of the nesting of different
           kinds of blocks within each other.  The type of block ("init", "once", etc.) is passed
           via the "block_type" parameter.

       end_block(block_type => <string>)
           This method is called by the Lexer when it encounters a closing Mason block tag like
           "</%perl>" or "</%args>".  Like "start_block()", its main purpose is to help maintain
           syntactic integrity.

       *_block(block => <string>, [ block_type => <string> ])
           Several compiler methods like "doc_block()", "text_block()", and "raw_block()" are
           called by the Lexer after "start_block()" when it encounters blocks of certain types.
           These methods actually do the work of putting the body of a block into the compiled
           data structure.

           The methods that follow this pattern are "init_block()", "perl_block()",
           "doc_block()", "text_block()", and "raw_block()".  The last method is called for all
           "<%once>", "<%cleanup>", "<%filter>", "<%init>", "<%perl>", and "<%shared>" blocks.

       text(text => <string>)
           Inserts the text contained in a "text" parameter into the component for verbatim
           output.

           This is called when the lexer finds plain text in a component.

       variable_declaration( type => <string>, name => <string>, default => <string> )
           Inserts a variable declaration from the "<%args>" section into the component.

           The type will be either "$", "@", or "%", indicating a scalar, array, or hash.  The
           name is the variable name without the leading sigil.  The default is everything found
           after the first "=>" on an "<%args>" block line, and may include a comment.

       key_value_pair(block_type => <string>, key => <string>, value => <string>)
           Inserts a key-value pair from a "<%flags>" or "<%attr>" section into the component.

           The "block_type" parameter will be either "flags" or "attr".

       start_named_block(block_type => <string>, name => <name>)
           Analogous to item_start_block, but starts a "named" block ("<%method>" or "<%def>").

       end_named_block()
           Called by the Lexer to end a "named" block.

       substitution(substitution => <string>, escape => <string>)
           Called by the Lexer when it encounters a substitution tag ("<% ... %>").

           The value of the "escape" parameter will be everything found after the pipe (|) in the
           substitution tag, and may be more than one character such as "nh".

       component_call(call => <string>)
           Called by the Lexer when it encounters a component call tag without embedded content
           ("<& ... &>").

           The "call" parameter contains the entire contents of the tag.

       component_content_call(call => <string>)
           Called by the Lexer when it encounters a component call tag with embedded content
           ("<&| ... &>").

       component_content_call_end()
           Called by the Lexer when it encounters an ending tag for a component call with content
           ("</&>").  Note that there is no corresponding "component_call_end()" method for
           component calls without content, because these calls don't have ending tags.

       perl_line(line => <string>)
           Called by the Lexer when it encounters a "%"-line.

SUBCLASSING

       We recommend that any parameters you add to Compiler be read-only, because the compiler
       object_id is only computed once on creation and would not reflect any changes to Lexer
       parameters.