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(slib.info)Precedence Parsing Overview

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Precedence Parsing Overview
---------------------------

This package offers improvements over previous parsers.

   * Common computer language constructs are concisely specified.

   * Grammars can be changed dynamically.  Operators can be assigned
     different meanings within a lexical context.

   * Rulesets don't need compilation.  Grammars can be changed
     incrementally.

   * Operator precedence is specified by integers.

   * All possibilities of bad input are handled (1) and return as much
     structure as was parsed when the error occured; The symbol `?' is
     substituted for missing input.

Here are the higher-level syntax types and an example of each.
Precedence considerations are omitted for clarity.  See Note: Grammar
Rule Definition for full details.

 - Grammar: nofix bye exit
          bye
     calls the function `exit' with no arguments.

 - Grammar: prefix - negate
          - 42
     Calls the function `negate' with the argument `42'.

 - Grammar: infix - difference
          x - y
     Calls the function `difference' with arguments `x' and `y'.

 - Grammar: nary + sum
          x + y + z
     Calls the function `sum' with arguments `x', `y', and `y'.

 - Grammar: postfix ! factorial
          5 !
     Calls the function `factorial' with the argument `5'.

 - Grammar: prestfix set set!
          set foo bar
     Calls the function `set!' with the arguments `foo' and `bar'.

 - Grammar: commentfix /* */
          /* almost any text here */
     Ignores the comment delimited by `/*' and `*/'.

 - Grammar: matchfix { list }
          {0, 1, 2}
     Calls the function `list' with the arguments `0', `1', and `2'.

 - Grammar: inmatchfix ( funcall )
          f(x, y)
     Calls the function `funcall' with the arguments `f', `x', and `y'.

 - Grammar: delim ;
          set foo bar;
     delimits the extent of the restfix operator `set'.

  ---------- Footnotes ----------

  (1) How do I know this?  I parsed 250kbyte of random input (an e-mail
file) with a non-trivial grammar utilizing all constructs.