Project Description

Hime Parser Generator generates lexers and parsers in C# 2.0 for given grammars. Hime supports a wide range of parsing methods: LR(0), LR(1), LALR(1), RNGLR(1), RNGLALR(1) and LR(*).
The tool itself is developed in C#. Lexers and parsers can be generated either by the command line tool, or programmatically by using the library.

Features

• Grammar inheritance (grammars can inherit rules, symbols, etc. from other grammars).
• Can generate documentation for the grammars (HTML pages for the grammar and the automata, visuals for the automata).
• Lexer: Enhanced regular expression language
  • always generates a minimal DFA for maximum speed
  • use usual operators: ?, *, +, |, as well as {n} to specify a specific count of matches and {m, n} to specify a range of matches count.
  • easily exclude expressions with the language difference operator: exp1 - exp2 will only match exp1 and exclude all matches of exp2
  • easily specify non-printable characters using unicode values (0x1234) or unicode ranges: 0x1234 .. 0x5678
  • use unicode character blocks: \ub{IsGreek}
  • use unicode character classes: \uc{Lu}
• Parser: Enhanced context-free grammar language
  • use regexp-like operators: *, +, ?, |
  • write template rules: head<param> -> TERMINAL param variable<param> ;
    • you may specify multiple parameters
    • parameters can be used directly in the rule definition or as values for the instantiation of other templates

Grammar Debugging

The Hime Parser Generator outputs a log as an MHTML file for the grammar compilation process (-l option in the command line). This log will report grammar conflicts that are still unresolved. The log gives useful information regarding the conflicts, helping you solve them.



As shown in the picture above, for each conflict the log will report:

• The state where the conflict is occuring, so that you can look it up in the generated grammar documentation (-d option in the command line)
• The conflictuous lookahead
• The list of conflictuous items
• Examples of input which are ambiguous according to this conflict

Grammar documentation

The Hime Parser Generator outputs a documentation as a MHTML file for the grammar that is being compiler (use the -d option in the command line). This documentation contains:

• The complete set of "flat" grammar rules with syntax highlightings.
• The generated LR graph in the form of a network of hyperlinked web pages containing for each state a detailed description of the state's items.

The picture hereafter shows an example of what is obtained with the grammar of the ANSI C language:






Hereafter is shown an example of a generated web page for a given state in the LR graph:
As can be seen in the picture, each item of the state is detailed with:

• An icon indicating whether this item is part of a conflict.
• The action (SHIFT or REDUCE) for the item. An hyperlink to the next state is given in the case of SHIFT actions.
• The item's grammar rule with the dot position.
• The item's lookaheads