Provided by: pccts_1.33MR33-6build1_amd64 bug


       antlr - ANother Tool for Language Recognition


       antlr [options] grammar_files


       Antlr  converts  an  extended form of context-free grammar into a set of C functions which
       directly implement an efficient form  of  deterministic  recursive-descent  LL(k)  parser.
       Context-free  grammars  may  be  augmented with predicates to allow semantics to influence
       parsing; this allows a form of context-sensitive parsing.  Selective backtracking is  also
       available  to  handle  non-LL(k)  and  even non-LALR(k) constructs.  Antlr also produces a
       definition of a lexer which can be automatically converted into C  code  for  a  DFA-based
       lexer  by  dlg.   Hence,  antlr  serves  a function much like that of yacc, however, it is
       notably more flexible and is more  integrated  with  a  lexer  generator  (antlr  directly
       generates dlg code, whereas yacc and lex are given independent descriptions).  Unlike yacc
       which accepts LALR(1) grammars, antlr accepts LL(k) grammars in an extended BNF notation —
       which eliminates the need for precedence rules.

       Like  yacc  grammars,  antlr  grammars  can  use automatically-maintained symbol attribute
       values referenced as dollar variables.  Further, because antlr generates top-down parsers,
       arbitrary  values  may  be  inherited from parent rules (passed like function parameters).
       Antlr also has a mechanism for creating and manipulating abstract-syntax-trees.

       There are various other niceties in antlr, including the ability  to  spread  one  grammar
       over  multiple files or even multiple grammars in a single file, the ability to generate a
       version of the grammar with actions stripped out (for documentation  purposes),  and  lots


       -ck n  Use  up  to  n  symbols  of  lookahead when using compressed (linear approximation)
              lookahead.  This type of lookahead is very cheap to compute and is attempted before
              full  LL(k)  lookahead,  which  is of exponential complexity in the worst case.  In
              general, the compressed lookahead can be much deeper (e.g, -ck 10)  than  the  full
              lookahead (which usually must be less than 4).

       -CC    Generate C++ output from both ANTLR and DLG.

       -cr    Generate a cross-reference for all rules.  For each rule, print a list of all other
              rules that reference it.

       -e1    Ambiguities/errors shown in low detail (default).

       -e2    Ambiguities/errors shown in more detail.

       -e3    Ambiguities/errors shown in excruciating detail.

       -fe file
              Rename err.c to file.

       -fh file
              Rename stdpccts.h header (turns on -gh) to file.

       -fl file
              Rename lexical output, parser.dlg, to file.

       -fm file
              Rename file with lexical mode definitions, mode.h, to file.

       -fr file
              Rename file which remaps globally visible symbols, remap.h, to file.

       -ft file
              Rename tokens.h to file.

       -ga    Generate ANSI-compatible code (default case).  This has not been rigorously  tested
              to  be  ANSI  XJ11  C  compliant,  but  it is close.  The normal output of antlr is
              currently compilable under both K&R, ANSI  C,  and  C++—this  option  does  nothing
              because  antlr generates a bunch of #ifdef's to do the right thing depending on the

       -gc    Indicates that antlr should generate no C code, i.e., only perform analysis on  the

       -gd    C  code is inserted in each of the antlr generated parsing functions to provide for
              user-defined handling of a detailed parse trace.  The  inserted  code  consists  of
              calls  to  the  user-supplied  macros or functions called zzTRACEIN and zzTRACEOUT.
              The only argument is a char * pointing to a C-style string  which  is  the  grammar
              rule recognized by the current parsing function.  If no definition is given for the
              trace functions, upon rule entry and exit, a message  will  be  printed  indicating
              that a particular rule as been entered or exited.

       -ge    Generate an error class for each non-terminal.

       -gh    Generate  stdpccts.h  for non-ANTLR-generated files to include.  This file contains
              all defines needed to describe the type of parser generated by antlr (e.g. how much
              lookahead is used and whether or not trees are constructed) and contains the header
              action specified by the user.

       -gk    Generate parsers that delay lookahead fetches until needed.  Without  this  option,
              antlr generates parsers which always have k tokens of lookahead available.

       -gl    Generate  line  info  about  grammar  actions in C parser of the form # line "file"
              which makes error messages from the C/C++ compiler make more  sense  as  they  will
              point into the grammar file not the resulting C file.  Debugging is easier as well,
              because you will step through the grammar not C file.

       -gs    Do not generate sets for token expression lists; instead  generate  a  ||-separated
              sequence of LA(1)==token_number.  The default is to generate sets.

       -gt    Generate code for Abstract-Syntax Trees.

       -gx    Do  not  create  the  lexical  analyzer files (dlg-related).  This option should be
              given when the user wishes to provide a customized lexical analyzer.  It  may  also
              be  used  in  make scripts to cause only the parser to be rebuilt when a change not
              affecting the lexical structure is made to the input grammars.

       -k n   Set k of LL(k) to n; i.e. set tokens of look-ahead (default==1).

       -o dir Directory where output files should  go  (default=".").   This  is  very  nice  for
              keeping the source directory clear of ANTLR and DLG spawn.

       -p     The  complete  grammar,  collected from all input grammar files and stripped of all
              comments and embedded actions, is listed to stdout.  This is  intended  to  aid  in
              viewing  the  entire  grammar  as a whole and to eliminate the need to keep actions
              concisely stated so that the grammar is easier to read.  Hence, it is preferable to
              embed  even  complex  actions  directly in the grammar, rather than to call them as
              subroutines, since the subroutine call overhead will be saved.

       -pa    This option is the same as -p except that the output is annotated  with  the  first
              sets determined from grammar analysis.

       -prc on
              Turn on the computation and hoisting of predicate context.

       -prc off
              Turn off the computation and hoisting of predicate context.  This option makes 1.10
              behave like the 1.06 release with option -pr on.  Context  computation  is  off  by

       -rl n  Limit   the   maximum  number  of  tree  nodes  used  by  grammar  analysis  to  n.
              Occasionally, antlr is unable to analyze a grammar submitted  by  the  user.   This
              rare situation can only occur when the grammar is large and the amount of lookahead
              is greater than one.  A nonlinear analysis algorithm is used by PCCTS to handle the
              general  case  of  LL(k)  parsing.  The average complexity of analysis, however, is
              near linear due to some fancy footwork in  the  implementation  which  reduces  the
              number  of  calls to the full LL(k) algorithm.  An error message will be displayed,
              if this limit is reached, which indicates the grammar construct being analyzed when
              antlr  hit  a non-linearity.  Use this option if antlr seems to go out to lunch and
              your disk start thrashing; try n=10000 to start.  Once the offending construct  has
              been identified, try to remove the ambiguity that antlr was trying to overcome with
              large  lookahead  analysis.   The  introduction  of  (...)?   backtracking   blocks
              eliminates  some of these problems — antlr does not analyze alternatives that begin
              with (...)? (it simply backtracks, if necessary, at run time).

       -w1    Set low warning level.  Do not warn if semantic predicates and/or (...)? blocks are
              assumed to cover ambiguous alternatives.

       -w2    Ambiguous  parsing  decisions  yield warnings even if semantic predicates or (...)?
              blocks are used.  Warn  if  predicate  context  computed  and  semantic  predicates
              incompletely disambiguate alternative productions.

       -      Read grammar from standard input and generate stdin.c as the parser file.


       Antlr  works...   we  think.   There  is no implicit guarantee of anything.  We reserve no
       legal rights to the software known as the Purdue Compiler Construction Tool Set (PCCTS)  —
       PCCTS  is  in  the public domain.  An individual or company may do whatever they wish with
       source code distributed  with  PCCTS  or  the  code  generated  by  PCCTS,  including  the
       incorporation  of  PCCTS,  or its output, into commercial software.  We encourage users to
       develop software with PCCTS.  However, we do ask that credit is given to us for developing
       PCCTS.   By  "credit",  we  mean  that if you incorporate our source code into one of your
       programs (commercial product, research project, or otherwise) that  you  acknowledge  this
       fact  somewhere  in the documentation, research report, etc...  If you like PCCTS and have
       developed a nice tool with the output, please mention that you developed it  using  PCCTS.
       As  long as these guidelines are followed, we expect to continue enhancing this system and
       expect to make other tools available as they are completed.


       *.c    output C parser.

       *.cpp  output C++ parser when C++ mode is used.

              output dlg lexical analyzer.

       err.c  token string array, error sets and error support routines.  Not used in C++ mode.

              file that redefines all globally visible parser symbols.  The use  of  the  #parser
              directive creates this file.  Not used in C++ mode.

              list of definitions needed by C files, not generated by PCCTS, that reference PCCTS
              objects.  This is not generated by default.  Not used in C++ mode.

              output #defines for tokens used and function prototypes for functions generated for


       dlg(1), pccts(1)