PARSING WORDS in parsing.fs and parsing-ext.c
Version 0.8.3
dnw 27-Feb-09

Our naming policy tries to distinguish three kinds of parsing:
ANS Forth strings, the parse area, and the input stream (across
line ends).  Words with "PARSE" or ">IN" in the name parse the
parse area.  Words with "INSTREAM" in the name parse the input
stream across lines or blocks.  Words with neither, with
exceptions like (*, parse strings.

Words that take a single character or whitespace as parsing
delimiter have no prefix.  Those that take a string pattern have
the prefix "S-", and those that take any of a null-terminated
set of characters have the prefix "{}".

In words with "SCAN" in the name, motion stops at the first
character of the delimiter, and no flag is left.  In words with
"SEEK" in the name, motion stops at the first character after
the delimiter, or off end, and a flag is left.  In words with
"SEPARATE" in the name, the delimiter is excluded from the
output, and a flag is left.

At present the pfe external module parsing-ext.c implements a
few more words than the ANS Forth implementation parse.fs.

LIBRARY STRING

  PARSING-LIB-S

ANS FORTH STRINGS

  ToolBelt 2002:
  STRING/  END-C@  SKIP  SCAN
  TRIM| [aka TRIM]
  SCAN-BACK [aka BACK]
  WHITE? [aka Is-White]

  ToolBelt 2000:
  /SPLIT
  S-STARTS [aka STARTS?]  S-ENDS [aka ENDS?]

  Other string extensions:
  CUT-FIRST  CUT-LAST  KEEP-FIRST  KEEP-LAST
  SKIP-BACK  |TRIM  |TRIM|  SEEK
  {}IN  {}SCAN  {}SEEK  {}STARTS  {}ENDS
  SEPARATE  {}SEPARATE  S-SEPARATE 
  S-AFTER  FIRST-WORD  SEPARATE-WORD
  WHITE-DELIMITED?

    PFE only:
    S-STARTS-NC  S-ENDS-NC

    Not implemented:
    STARTS  STARTS-NC  ENDS  ENDS-NC
    {}SKIP  S-SKIP  S-SCAN  S-SEEK

INPUT STREAM

  Parse area:
  PARSE-AREA@  PARSE-AREA!  EMPTY-PARSE-AREA  PARSE-AREA-EMPTY?
  PARSE-NAME  PREPARSE-NAME PARSE-NAME-AWAY
  >IN++  >IN--

    Defined in parsing-test.fs:
    >IN+  >IN-

    PFE only:
    SPACE|PUNCT-PARSE

    Not implemented:
    {}PARSE  S-PARSE  PARSE-AWAY  {}PARSE-AWAY

  Across lines or blocks:
  \\  ?EMIT-CR  NEXT-INSTREAM-NAME
  S-SEEK-INSTREAM  |S|-SEEK-INSTREAM  (*

    Not implemented:
    SKIP-INSTREAM  SCAN-INSTREAM  SEEK-INSTREAM
    {}SKIP-INSTREAM  {}SCAN-INSTREAM  {}SEEK-INSTREAM