-------------------------------------------------------------------------------
---  HIGHLIGHT PLUGIN MANUAL - Version 3.9    -------------------- May 2012 ---
-------------------------------------------------------------------------------

CONTENT
-------------------------------------------------------------------------------

1. SCRIPT STRUCTURE
2. SYNTAX CHUNK ELEMENTS
   2.1 FUNCTION ONSTATECHANGE
   2.2 FUNCTION ADDKEYWORD
   2.3 FUNCTION DECORATE
3. THEME CHUNK ELEMENTS
4. EXAMPLES
5. PLUG-IN USAGE


1. SCRIPT STRUCTURE
-------------------------------------------------------------------------------

The following script contains a minimal plug-in which has no effect on the
output, since all update functions have empty definitions:

Description="NOOP plugin"

-- optional parameter: syntax description
function syntaxUpdate(desc)
end

-- optional parameter: theme description
function themeUpdate(desc)
end

Plugins={
  { Type="theme", Chunk=themeUpdate },
  { Type="lang", Chunk=syntaxUpdate },
}

The first line contains a description which gives a short summary of the
plug-in effects.

The next lines contain function definitions:
The syntaxUpdate function is applied on syntax definition scripts (*.lang),
whereas the themeUpdate function is applied on colour themes (*.theme).
The desc parameter contains the description string of the loaded syntax
definition or colour theme. This information can be used to restrict
modifications to certain kinds of input (i.e. only C code should be
enhanced with syslog keywords).

Finally the Plugins array connects the functions to the Lua states which 
are created when highlight loads a lang or theme script. In this example,
themeUpdate is connected to the theme state, and syntaxUpdate to the lang
state. It is not required to always define both connections if your plugin
only affects one of the config script types.


2. SYNTAX CHUNK ELEMENTS
-------------------------------------------------------------------------------

The following list includes all variables and constants you may use to adjust 
the parser's syntax highlighting.

Items available in the syntax chunk:

Comments: table
Description: string
Digits: string
EnableIndentation: boolean
Identifiers: string
IgnoreCase: boolean
Keywords: table
NestedSections: table
Operators: string
PreProcessor: table
Strings: table

Read only:

HL_LANG_DIR: string
HL_BLOCK_COMMENT: number
HL_BLOCK_COMMENT_END: number
HL_EMBEDDED_CODE_BEGIN: number
HL_EMBEDDED_CODE_END: number
HL_ESC_SEQ: number
HL_ESC_SEQ_END: number
HL_IDENTIFIER_BEGIN: number
HL_IDENTIFIER_END: number
HL_KEYWORD: number
HL_KEYWORD_END: number
HL_LINENUMBER: number
HL_LINE_COMMENT: number
HL_LINE_COMMENT_END: number
HL_NUMBER: number
HL_OPERATOR: number
HL_OPERATOR_END: number
HL_PREPROC: number
HL_PREPROC_END: number
HL_PREPROC_STRING: number
HL_STANDARD: number
HL_STRING: number
HL_STRING_END: number
HL_UNKNOWN: number

HL_OUTPUT: number
HL_FORMAT_HTML: number
HL_FORMAT_XHTML: number
HL_FORMAT_TEX: number
HL_FORMAT_LATEX: number
HL_FORMAT_RTF: number
HL_FORMAT_ANSI: number
HL_FORMAT_XTERM256: number
HL_FORMAT_SVG: number
HL_FORMAT_BBCODE: number

Functions:

AddKeyword: function
OnStateChange: function
Decorate: function



IMPORTANT: Functions will only be executed if they are defined as local
functions within the lang chunk function referenced in the Plugins array. 
They will be ignored when defined elsewhere in the plug-in script.


2.1 FUNCTION ONSTATECHANGE
-------------------------------------------------------------------------------

This function is a hook which is called if an internal state changes (e.g. from
HL_STANDARD to HL_KEYWORD if a keyword is found). It can be used to alter
the new state or to manipulate syntax elements.

OnStateChange(oldState, newState, token, kwGroupID)

  Hook Event: Highlighting parser state change
  Parameters: oldState:  old state
              newState:  intended new state
              token:     the current token which triggered
	                 the new state
              kwGroupID: if newState is HL_KEYWORD, the parameter
                         contains the keyword group ID
  Returns:    Correct state to continue

Examples:

function OnStateChange(oldState, newState, token, kwgroup)
   if newState==HL_KEYWORD and kwgroup==5 then
      AddKeyword(token, 5)
   end
   return newState
end

This function adds the current keyword to the internal keyword list if
the keyword belongs to keyword group 5. If keyword group 5 is defined by a regex,
this token will be recognized later as keyword even if the regular expression does
no longer match.

function OnStateChange(oldState, newState, token)
   if token=="]]" and oldState==HL_STRING and newState==HL_BLOCK_COMMENT_END then
      return HL_STRING_END
   end
   return newState
end

This function resolves a Lua parsing issue with the "]]" close delimiter which
ends both comments and strings.


2.2 FUNCTION ADDKEYWORD
-------------------------------------------------------------------------------

This function will add a keyword to one of the the internal keyword lists.
It has no effect if the keyword was added before.
Keywords added with AddKeyword will remain active for all files of the same
syntax if highlight is in batch mode.

AddKeyword(keyword, kwGroupID)

  Parameters: keyword:   string which should be added to a keyword list
              kwGroupID: keyword group ID of the keyword
  Returns:    true if successfull


2.3 FUNCTION DECORATE
-------------------------------------------------------------------------------

This function is a hook which is called if a syntax token has been identified.
It can be used to alter the token or to add additional text in the target output
format (e.g. hyperlinks). Important: The return value of Decorate will be 
embedded in the formatting tags of the output format. The return value is not
modified or validated by highlight.

Decorate(token, state, kwGroupID)

  Hook Event: Token identification
  Parameters: token:     the current token
	      state:     the current state
              kwGroupID: if state is HL_KEYWORD, the parameter
                         contains the keyword group ID
  Returns:    Altered token string or nothing if original token should be 
              outputted

Examples:

function Decorate(token, state)
  if (state == HL_KEYWORD) then
    return  string.upper(token)
  end
end

This function converts all keywords to upper case.


knowntags={}
file = assert(io.open(HL_INPUT_FILE, "r"))
-- read file and fill knowntags

function Decorate(token, state, kwclass)
  for k,v in pairs(knowntags) do
    if k==token  then
      return '<span title="'..v..'">'..token .. '</span>'
    end
  end
end

This function adds tooltips to keywords which were found in a given tags file.


3. THEME CHUNK ELEMENTS
-------------------------------------------------------------------------------

The following list includes all items you may overwrite or extend to adjust
the formatting (colour and font attributes) of the output:

Default: table
Canvas: table
Number: table
Escape: table
String: table
StringPreProc: table
BlockComment: table
PreProcessor: table
LineNum: table
Operator: table
LineComment: table
Keywords: table
Injections: table

Read only:

HL_OUTPUT: number
HL_FORMAT_HTML: number
HL_FORMAT_XHTML: number
HL_FORMAT_TEX: number
HL_FORMAT_LATEX: number
HL_FORMAT_RTF: number
HL_FORMAT_ANSI: number
HL_FORMAT_XTERM256: number
HL_FORMAT_SVG: number
HL_FORMAT_BBCODE: number


4. EXAMPLES
-------------------------------------------------------------------------------

The plugins directory contains some example scripts which show the
functionality explained above:

bash_functions.lua
Description: Add function names to keyword list
Features:    Adds new keyword group based on a regex, defines OnStateChange,
             uses AddKeyword

cpp_qt.lua, cpp_syslog.lua, cpp_wx.lua, java_library.lua
Description: *
Features:    Adds and extends keyword groups based on lists and regexes

theme_invert.lua
Description: Invert colours of the original theme
Features:    Modifies all color attributes of the theme script, uses Lua
             pattern matching
          
cpp_ref_cplusplus_com.lua
Description: Add qtproject.org reference links to HTML, LaTeX or RTF output of
             C++ code
Features:    Uses Decorate to add hyperlinks for a defined set of C++ keywords.
             Adds CSS styles with Injections.

ctags_html_tooltips.lua
Description: Add tooltips based on a ctags file (default input file: tags)
Features:    Uses file input (defined by cli option --plug-in-read) and
             parses tags data before Decorate is called.
		  
5. PLUG-IN USAGE
-------------------------------------------------------------------------------

Command line interface:
Use --plug-in to load a plug-in script file. This option can be applied 
repeatedly to apply several plug-ins.

GUI:
Add the plug-in scripts in the plug-in selection tab and enable them using the
checkboxes.