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Push parsing for java...
|
From: |
Dennis Heimbigner |
|
Subject: |
Push parsing for java... |
|
Date: |
Wed, 12 Sep 2012 15:22:39 -0600 |
|
User-agent: |
Thunderbird 2.0.0.24 (Windows/20100228) |
For my own use, I created a modified
version of lalr1.java to support push
parsing. It is attached in case
anyone has any use for it. Also
a couple of test cases.
Note that I have extensively modified
lalr1.java to remove the extraneous
m4 escaping. I think the result is
a much cleaner and more readable skeleton.
But your mileage may vary.
=Dennis Heimbigner
Unidata/UCAR
# Java skeleton for Bison -*- autoconf -*-
# Copyright (C) 2007-2012 Free Software Foundation, Inc.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
m4_include(b4_pkgdatadir/[java.m4])
b4_defines_if([b4_fatal([%s: %%defines does not make sense in Java],
[b4_skeleton])])
m4_ifval(m4_defn([b4_symbol_destructors]),
[b4_fatal([%s: %%destructor does not make sense in Java],
[b4_skeleton])],
[])
m4_divert_push(0)dnl
@output(b4_parser_file_name@)@
b4_copyright([Skeleton implementation for Bison LALR(1) parsers in Java],
[2007-2012])
dnl
dnl # Check the value of %define api.push-pull.
b4_percent_define_default([[api.push-pull]], [[pull]])dnl
b4_percent_define_check_values([[[[api.push-pull]],
[[pull]], [[push]], [[both]]]])dnl
b4_define_flag_if([pull]) m4_define([b4_pull_flag], [[1]])dnl
b4_define_flag_if([push]) m4_define([b4_push_flag], [[1]])dnl
m4_case(b4_percent_define_get([[api.push-pull]]),
[pull], [m4_define([b4_push_flag], [[0]])],
[push], [m4_define([b4_pull_flag], [[0]])])dnl
dnl
dnl # Handle BISON_USE_PUSH_FOR_PULL for the test suite. So that push parsing
dnl # tests function as written, do not let BISON_USE_PUSH_FOR_PULL modify the
dnl # behavior of Bison at all when push parsing is already requested.
b4_define_flag_if([use_push_for_pull])dnl
b4_use_push_for_pull_if([b4_push_if([m4_define([b4_use_push_for_pull_flag],
[[0]])],[m4_define([b4_push_flag], [[1]])])])dnl
m4_define([b4_both_if],[b4_push_if([b4_pull_if([$1],[$2])],[$2])])dnl
m4_define([b4_throw_exception],[m4_ifval($1,[throw new $1($2);],[$3;])])
b4_percent_define_ifdef([package], [package b4_percent_define_get([package]);])
/* First part of user declarations. */
b4_pre_prologue
b4_percent_code_get([[imports]])
/**
* A Bison parser, automatically generated from <tt>m4_bpatsubst(b4_file_name,
[^"\(.*\)"$], [\1])</tt>.
*
* @@author LALR (1) parser skeleton written by Paolo Bonzini.
*/
b4_public_if([public ])dnl
b4_abstract_if([abstract ])dnl
b4_final_if([final ])dnl
b4_strictfp_if([strictfp ])dnl
class b4_parser_class_name[]dnl
b4_percent_define_get3([extends], [ extends ])dnl
b4_percent_define_get3([implements], [ implements ])
{
b4_identification
/** True if verbose error messages are enabled. */
public boolean errorVerbose = b4_flag_value([error_verbose]);
b4_locations_if([ /**
* A class defining a pair of positions. Positions, defined by the
* <code>b4_position_type</code> class, denote a point in the input.
* Locations represent a part of the input through the beginning
* and ending positions. */
public class b4_location_type {
/** The first, inclusive, position in the range. */
public b4_position_type begin;
/** The first position beyond the range. */
public b4_position_type end;
/**
* Create a <code>b4_location_type</code> denoting an empty range located at
* a given point.
* @@param loc The position at which the range is anchored. */
public b4_location_type (b4_position_type loc) {
this.begin = this.end = loc;
}
/**
* Create a <code>b4_location_type</code> from the endpoints of the range.
* @@param begin The first position included in the range.
* @@param end The first position beyond the range. */
public b4_location_type (b4_position_type begin, b4_position_type end) {
this.begin = begin;
this.end = end;
}
/**
* Print a representation of the location. For this to be correct,
* <code>b4_position_type</code> should override the <code>equals</code>
* method. */
public String toString () {
if (begin.equals (end))
return begin.toString ();
else
return begin.toString () + "-" + end.toString ();
}
}
])dnl
/** Token returned by the scanner to signal the end of its input. */
public static final int EOF = 0;
b4_token_enums(b4_tokens)
b4_locations_if([
private b4_location_type yylloc (YYStack rhs, int n)
{
if (n > 0)
return new b4_location_type (rhs.locationAt (n-1).begin, rhs.locationAt
(0).end);
else
return new b4_location_type (rhs.locationAt (0).end);
}])
/**
* Communication interface between the scanner and the Bison-generated
* parser <tt>b4_parser_class_name</tt>.
*/
public interface Lexer {
b4_locations_if([/**
* Method to retrieve the beginning position of the last scanned token.
* @@return the position at which the last scanned token starts. */
b4_position_type getStartPos ();
/**
* Method to retrieve the ending position of the last scanned token.
* @@return the first position beyond the last scanned token. */
b4_position_type getEndPos ();])
/**
* Method to retrieve the semantic value of the last scanned token.
* @@return the semantic value of the last scanned token. */
b4_yystype getLVal ();
/**
* Entry point for the scanner. Returns the token identifier corresponding
* to the next token and prepares to return the semantic value
* b4_locations_if([and beginning/ending positions ])of the token.
* @@return the token identifier corresponding to the next token. */
int yylex () b4_maybe_throws([b4_lex_throws]);
/**
* Entry point for error reporting. Emits an error
* b4_locations_if([referring to the given location ])in a user-defined way.
*
* b4_locations_if([[@@param loc The location of the element to which the
* error message is related]])
* @@param s The string for the error message. */
void yyerror (b4_locations_if([b4_location_type loc, ])String s);
}
b4_lexer_if([private class YYLexer implements Lexer {
b4_percent_code_get([[lexer]])
}
])/** The object doing lexical analysis for us. */
private Lexer yylexer;
b4_parse_param_vars
b4_lexer_if([
/**
* Instantiates the Bison-generated parser.
*/
public b4_parser_class_name (b4_parse_param_decl([b4_lex_param_decl])) {
this.yylexer = new YYLexer(b4_lex_param_call);
b4_parse_param_cons
}
])
/**
* Instantiates the Bison-generated parser.
* @@param yylexer The scanner that will supply tokens to the parser.
*/
b4_lexer_if([protected], [public]) b4_parser_class_name
(b4_parse_param_decl([Lexer yylexer])) {
this.yylexer = yylexer;
b4_parse_param_cons
}
b4_push_if([
/**
* Instantiates the Bison-generated parser with no lexer.
* Only generated if this is a push parser.
*/
public b4_parser_class_name () {
b4_parse_param_cons
}
])dnl
private java.io.PrintStream yyDebugStream = System.err;
/**
* Return the <tt>PrintStream</tt> on which the debugging output is
* printed.
*/
public final java.io.PrintStream getDebugStream () { return yyDebugStream; }
/**
* Set the <tt>PrintStream</tt> on which the debug output is printed.
* @@param s The stream that is used for debugging output.
*/
public final void setDebugStream(java.io.PrintStream s) { yyDebugStream = s; }
private int yydebug = 0;
/**
* Answer the verbosity of the debugging output; 0 means that all kinds of
* output from the parser are suppressed.
*/
public final int getDebugLevel() { return yydebug; }
/**
* Set the verbosity of the debugging output; 0 means that all kinds of
* output from the parser are suppressed.
* @@param level The verbosity level for debugging output.
*/
public final void setDebugLevel(int level) { yydebug = level; }
private final int yylex () b4_maybe_throws([b4_lex_throws]) {
return yylexer.yylex ();
}
protected final void yyerror (b4_locations_if([b4_location_type[ loc,
]])String s) {
yylexer.yyerror (b4_locations_if([loc, ])s);
}
b4_locations_if([
protected final void yyerror (String s) {
yylexer.yyerror ((b4_location_type)null, s);
}
protected final void yyerror (b4_position_type loc, String s) {
yylexer.yyerror (new b4_location_type (loc), s);
}])
protected final void yycdebug (String s) {
if (yydebug > 0)
yyDebugStream.println (s);
}
private final class YYStack {
private int[[]] stateStack = new int[[16]];
b4_locations_if([private b4_location_type[[]] locStack = new
b4_location_type[[16]];])
private b4_yystype[[]] valueStack = new b4_yystype[[16]];
public int size = 16;
public int height = -1;
public final void push (int state, b4_yystype value[]dnl
b4_locations_if([, b4_location_type loc])) {
height++;
if (size == height)
{
int[[]] newStateStack = new int[[size * 2]];
System.arraycopy (stateStack, 0, newStateStack, 0, height);
stateStack = newStateStack;
b4_locations_if([
b4_location_type[[]] newLocStack = new b4_location_type[[size * 2]];
System.arraycopy (locStack, 0, newLocStack, 0, height);
locStack = newLocStack;])
b4_yystype[[]] newValueStack = new b4_yystype[[size * 2]];
System.arraycopy (valueStack, 0, newValueStack, 0, height);
valueStack = newValueStack;
size *= 2;
}
stateStack[[height]] = state;
b4_locations_if([locStack[[height]] = loc;])
valueStack[[height]] = value;
}
public final void pop () {
pop (1);
}
public final void pop (int num) {
// Avoid memory leaks... garbage collection is a white lie!
if (num > 0) {
java.util.Arrays.fill (valueStack, height - num + 1, height + 1, null);
b4_locations_if([java.util.Arrays.fill (locStack, height - num + 1,
height + 1, null);])
}
height -= num;
}
public final int stateAt (int i) {
return stateStack[[height - i]];
}dnl
dnl
b4_locations_if([public final b4_location_type locationAt (int i) {
return locStack[[height - i]];
}])
public final b4_yystype valueAt (int i) {
return valueStack[[height - i]];
}
// Print the state stack on the debug stream.
public void print (java.io.PrintStream out)
{
out.print ("Stack now");
for (int i = 0; i <= height; i++)
{
out.print (' ');
out.print (stateStack[[i]]);
}
out.println ();
}
public final void clear () {
if(height > 0) pop (height);
}
}
/**
* Returned by a Bison action in order to stop the parsing process and
* return success (<tt>true</tt>). */
public static final int YYACCEPT = 0;
/**
* Returned by a Bison action in order to stop the parsing process and
* return failure (<tt>false</tt>). */
public static final int YYABORT = 1;
b4_push_if([
/**
* Returned by a Bison action in order to stop the parsing process and
* return failure (<tt>false</tt>). */
public static final int YYMORE = 4;])
/**
* Returned by a Bison action in order to start error recovery without
* printing an error message. */
public static final int YYERROR = 2;
// Internal return codes that are not supported for user semantic
// actions.
private static final int YYERRLAB = 3;
private static final int YYNEWSTATE = 4;
private static final int YYDEFAULT = 5;
private static final int YYREDUCE = 6;
private static final int YYERRLAB1 = 7;
private static final int YYRETURN = 8;
private int yyerrstatus_ = 0;
/**
* Return whether error recovery is being done. In this state, the parser
* reads token until it reaches a known state, and then restarts normal
* operation. */
public final boolean recovering ()
{
return yyerrstatus_ == 0;
}
private int yyaction (int yyn, YYStack yystack, int yylen)
b4_maybe_throws([b4_throws])
{
b4_yystype yyval;
b4_locations_if([b4_location_type[ yyloc = yylloc (yystack, yylen);]])
/* If YYLEN is nonzero, implement the default value of the action:
`$$ = $1'. Otherwise, use the top of the stack.
Otherwise, the following line sets YYVAL to garbage.
This behavior is undocumented and Bison
users should not rely upon it. */
if (yylen > 0)
yyval = yystack.valueAt (yylen - 1);
else
yyval = yystack.valueAt (0);
yy_reduce_print (yyn, yystack);
switch (yyn)
{
b4_user_actions
default: break;
}
yy_symbol_print ("-> $$ =", yyr1_[[yyn]], yyval[]b4_locations_if([,
yyloc]));
yystack.pop (yylen);
yylen = 0;
/* Shift the result of the reduction. */
yyn = yyr1_[[yyn]];
int yystate = yypgoto_[[yyn - yyntokens_]] + yystack.stateAt (0);
if (0 <= yystate && yystate <= yylast_
&& yycheck_[[yystate]] == yystack.stateAt (0))
yystate = yytable_[[yystate]];
else
yystate = yydefgoto_[[yyn - yyntokens_]];
yystack.push (yystate, yyval[]b4_locations_if([, yyloc]));
return YYNEWSTATE;
}
/* Return YYSTR after stripping away unnecessary quotes and
backslashes, so that it's suitable for yyerror. The heuristic is
that double-quoting is unnecessary unless the string contains an
apostrophe, a comma, or backslash (other than backslash-backslash).
YYSTR is taken from yytname. */
private final String yytnamerr_ (String yystr)
{
if (yystr.charAt (0) == '"')
{
StringBuffer yyr = new StringBuffer ();
strip_quotes: for (int i = 1; i < yystr.length (); i++)
switch (yystr.charAt (i))
{
case '\'':
case ',':
break strip_quotes;
case '\\':
if (yystr.charAt(++i) != '\\')
break strip_quotes;
/* Fall through. */
default:
yyr.append (yystr.charAt (i));
break;
case '"':
return yyr.toString ();
}
}
else if (yystr.equals ("$end"))
return "end of input";
return yystr;
}
/*--------------------------------.
| Print this symbol on YYOUTPUT. |
`--------------------------------*/
private void yy_symbol_print (String s, int yytype,
b4_yystype yyvaluep[]dnl
b4_locations_if([, Object yylocationp]))
{
if (yydebug > 0)
yycdebug (s + (yytype < yyntokens_ ? " token " : " nterm ")
+ yytname_[[yytype]] + " ("b4_locations_if([
+ yylocationp + ": "])
+ (yyvaluep == null ? "(null)" : yyvaluep.toString ()) + ")");
}
m4_define([b4_define_state],[
/// Lookahead and lookahead in internal form.
int yychar = yyempty_;
int yytoken = 0;
/* State. */
int yyn = 0;
int yylen = 0;
int yystate = 0;
YYStack yystack = new YYStack ();
/* Error handling. */
int yynerrs_ = 0;
b4_locations_if([/// The location where the error started.
b4_location_type yyerrloc = null;
/// b4_location_type of the lookahead.
b4_location_type yylloc = new b4_location_type (null, null);
/// @@$.
b4_location_type yyloc;])
/// Semantic value of the lookahead.
b4_yystype yylval = null;
])
b4_push_if([
boolean push_parse_initialized = false;
// If using push parser, then define the state as instance variables
b4_define_state
public void push_parse_initialize()
{
yychar = yyempty_;
yytoken = 0;
yyn = 0;
yylen = 0;
yystate = 0;
yystack.clear();
yynerrs_ = 0;
yylval = null;
yyerrstatus_ =0;
b4_locations_if([ yyerrloc = null;
yylloc = new b4_location_type (null, null);])
m4_ifdef([b4_initial_action],
b4_dollar_pushdef([yylval], [], [yylloc])dnl
/* User initialization code. */
[b4_user_initial_action]
b4_dollar_popdef)dnl
/* Initialize the stack. */
yystack.push (yystate, yylval[]b4_locations_if([, yylloc]));
push_parse_initialized = true;
}
])
/**
* Parse input from the scanner that was specified at object construction
* time. Return whether the end of the input was reached successfully.
*
* @@return <tt>true</tt> if the parsing succeeds. Note that this does not
* imply that there were no syntax errors.
*/
b4_push_if([ public boolean parse ()
b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])
{
yycdebug ("Starting parse\n");
int status;
push_parse_initialize();
do {
status = push_parse(yylexer);
} while (status == YYMORE);
return (status == YYACCEPT);
}
],[ public boolean parse () b4_maybe_throws([b4_list2([b4_lex_throws],
[b4_throws])])
{
b4_define_state[]dnl
m4_ifdef([b4_initial_action],
b4_dollar_pushdef([yylval], [], [yylloc])dnl
/* User initialization code. */
[b4_user_initial_action]
b4_dollar_popdef)dnl
/* Initialize the stack. */
yystack.push (yystate, yylval[]b4_locations_if([, yylloc]));
yycdebug ("Starting parse\n");
])
b4_push_if([
/**
* Push Parse input from the scanner that was specified at object construction
* time.
*
* @@return <tt>YYACCEPT, YYABORT, or YYMORE</tt>
*/
public int push_parse () b4_maybe_throws([b4_list2([b4_lex_throws],
[b4_throws])])
{
return push_parse(yylexer);
}
])dnl
b4_push_if([
/**
* Push Parse input from the scanner argument
*
* @@param yylexer lexer from which to get next token
*
* @@return <tt>YYACCEPT, YYABORT, YYMORE</tt>
*/
public int push_parse (Lexer yylexer)
b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])
{
if(yylexer == null)
b4_throw_exception([b4_throws],["Null lexer"],[return YYABORT])
int token = yylexer.yylex();
b4_yystype lval = yylexer.getLVal();
b4_locations_if([b4_location_type yylloc
= new b4_location_type[](yylexer.getStartPos (),yylexer.getEndPos ());
return push_parse(token,lval,yylloc);],[
return push_parse(token,lval);])
}
])
b4_push_if([
/**
* Push Parse input from the scanner argument
*
* @@param yylextoken current token
* @@param yylexval current lval
b4_locations_if([ * @@param yyylexpos current position])
*
* @@return <tt>YYACCEPT, YYABORT, YYMORE</tt>
*/
b4_locations_if([
public int push_parse (int yylextoken, b4_yystype yylexval, b4_location_type
yylexloc)],[
public int push_parse (int yylextoken, b4_yystype yylexval)])
b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])
{
if(!push_parse_initialized) {push_parse_initialize();}
])
int label = YYNEWSTATE;
for(;;)
switch (label)
{
/* New state. Unlike in the C/C++ skeletons, the state is already
pushed when we come here. */
case YYNEWSTATE:
yycdebug ("Entering state " + yystate + "\n");
if (yydebug > 0)
yystack.print (yyDebugStream);
/* Accept? */
if (yystate == yyfinal_)
b4_push_if([ {label = YYACCEPT; break;}],[ return true;])
/* Take a decision. First try without lookahead. */
yyn = yypact_[[yystate]];
if (yy_pact_value_is_default_ (yyn))
{
label = YYDEFAULT;
break;
}
/* Read a lookahead token. */
if (yychar == yyempty_)
{
yycdebug ("Reading a token: ");
b4_push_if([
yychar = yylextoken;
yylval = yylexval;
b4_locations_if([yylloc = yylexloc;])],
[ yychar = yylex();
yylval = yylexer.getLVal ();
b4_locations_if([
yylloc = new b4_location_type[](yylexer.getStartPos (),
yylexer.getEndPos ());])
])
}
/* Convert token to internal form. */
if (yychar <= EOF)
{
yychar = yytoken = EOF;
yycdebug ("Now at end of input.\n");
}
else
{
yytoken = yytranslate_ (yychar);
yy_symbol_print ("Next token is", yytoken,
yylval[]b4_locations_if([, yylloc]));
}
/* If the proper action on seeing token YYTOKEN is to reduce or to
detect an error, take that action. */
yyn += yytoken;
if (yyn < 0 || yylast_ < yyn || yycheck_[[yyn]] != yytoken)
label = YYDEFAULT;
/* <= 0 means reduce or error. */
else if ((yyn = yytable_[[yyn]]) <= 0)
{
if (yy_table_value_is_error_ (yyn))
label = YYERRLAB;
else
{
yyn = -yyn;
label = YYREDUCE;
}
}
else
{
/* Shift the lookahead token. */
yy_symbol_print ("Shifting", yytoken,
yylval[]b4_locations_if([, yylloc]));
/* Discard the token being shifted. */
yychar = yyempty_;
/* Count tokens shifted since error; after three, turn off error
status. */
if (yyerrstatus_ > 0)
--yyerrstatus_;
yystate = yyn;
yystack.push (yystate, yylval[]b4_locations_if([, yylloc]));
b4_push_if([ label = YYRETURN;],[ label = YYNEWSTATE;])
}
break;
/*-----------------------------------------------------------.
| yydefault -- do the default action for the current state. |
`-----------------------------------------------------------*/
case YYDEFAULT:
yyn = yydefact_[[yystate]];
if (yyn == 0)
label = YYERRLAB;
else
label = YYREDUCE;
break;
/*-----------------------------.
| yyreduce -- Do a reduction. |
`-----------------------------*/
case YYREDUCE:
yylen = yyr2_[[yyn]];
label = yyaction (yyn, yystack, yylen);
yystate = yystack.stateAt (0);
break;
/*------------------------------------.
| yyerrlab -- here on detecting error |
`------------------------------------*/
case YYERRLAB:
/* If not already recovering from an error, report this error. */
if (yyerrstatus_ == 0)
{
++yynerrs_;
if (yychar == yyempty_)
yytoken = yyempty_;
yyerror (b4_locations_if([yylloc, ])yysyntax_error (yystate,
yytoken));
}
b4_locations_if([yyerrloc = yylloc;])
if (yyerrstatus_ == 3)
{
/* If just tried and failed to reuse lookahead token after an
error, discard it. */
if (yychar <= EOF)
{
/* Return failure if at end of input. */
if (yychar == EOF)
b4_push_if([ {label = YYABORT; break;}],[ return false;])
}
else
yychar = yyempty_;
}
/* Else will try to reuse lookahead token after shifting the error
token. */
label = YYERRLAB1;
break;
/*---------------------------------------------------.
| errorlab -- error raised explicitly by YYERROR. |
`---------------------------------------------------*/
case YYERROR:
b4_locations_if([yyerrloc = yystack.locationAt (yylen - 1);])
/* Do not reclaim the symbols of the rule which action triggered
this YYERROR. */
yystack.pop (yylen);
yylen = 0;
yystate = yystack.stateAt (0);
label = YYERRLAB1;
break;
/*-------------------------------------------------------------.
| yyerrlab1 -- common code for both syntax error and YYERROR. |
`-------------------------------------------------------------*/
case YYERRLAB1:
yyerrstatus_ = 3; /* Each real token shifted decrements this. */
for (;;)
{
yyn = yypact_[[yystate]];
if (!yy_pact_value_is_default_ (yyn))
{
yyn += yyterror_;
if (0 <= yyn && yyn <= yylast_ && yycheck_[[yyn]] == yyterror_)
{
yyn = yytable_[[yyn]];
if (0 < yyn)
break;
}
}
/* Pop the current state because it cannot handle the error token.
*/
if (yystack.height == 0)
b4_push_if([ {label = YYABORT; break;}],[ return false;])
b4_locations_if([yyerrloc = yystack.locationAt (0);])
yystack.pop ();
yystate = yystack.stateAt (0);
if (yydebug > 0)
yystack.print (yyDebugStream);
}
b4_locations_if([
/* Muck with the stack to setup for yylloc. */
yystack.push (0, null, yylloc);
yystack.push (0, null, yyerrloc);
yyloc = yylloc (yystack, 2);
yystack.pop (2);])
/* Shift the error token. */
yy_symbol_print ("Shifting", yystos_[[yyn]],
yylval[]b4_locations_if([, yyloc]));
yystate = yyn;
yystack.push (yyn, yylval[]b4_locations_if([, yyloc]));
b4_push_if([ label = YYRETURN;],[ label = YYNEWSTATE;])
break;
/* Accept. */
case YYACCEPT:
b4_push_if([ push_parse_initialized = false; return YYACCEPT;],[
return true;])
/* Abort. */
case YYABORT:
b4_push_if([ push_parse_initialized = false; return YYACCEPT;],[
return false;])
b4_push_if([ /* More. */
case YYRETURN:
return YYMORE;
])
}
}
// Generate an error message.
private String yysyntax_error (int yystate, int tok)
{
if (errorVerbose)
{
/* There are many possibilities here to consider:
- Assume YYFAIL is not used. It's too flawed to consider.
See
<http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
for details. YYERROR is fine as it does not invoke this
function.
- If this state is a consistent state with a default action,
then the only way this function was invoked is if the
default action is an error action. In that case, don't
check for expected tokens because there are none.
- The only way there can be no lookahead present (in tok) is
if this state is a consistent state with a default action.
Thus, detecting the absence of a lookahead is sufficient to
determine that there is no unexpected or expected token to
report. In that case, just report a simple "syntax error".
- Don't assume there isn't a lookahead just because this
state is a consistent state with a default action. There
might have been a previous inconsistent state, consistent
state with a non-default action, or user semantic action
that manipulated yychar. (However, yychar is currently out
of scope during semantic actions.)
- Of course, the expected token list depends on states to
have correct lookahead information, and it depends on the
parser not to perform extra reductions after fetching a
lookahead from the scanner and before detecting a syntax
error. Thus, state merging (from LALR or IELR) and default
reductions corrupt the expected token list. However, the
list is correct for canonical LR with one exception: it
will still contain any token that will not be accepted due
to an error action in a later state.
*/
if (tok != yyempty_)
{
// FIXME: This method of building the message is not compatible
// with internationalization.
StringBuffer res =
new StringBuffer ("syntax error, unexpected ");
res.append (yytnamerr_ (yytname_[[tok]]));
int yyn = yypact_[[yystate]];
if (!yy_pact_value_is_default_ (yyn))
{
/* Start YYX at -YYN if negative to avoid negative
indexes in YYCHECK. In other words, skip the first
-YYN actions for this state because they are default
actions. */
int yyxbegin = yyn < 0 ? -yyn : 0;
/* Stay within bounds of both yycheck and yytname. */
int yychecklim = yylast_ - yyn + 1;
int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
int count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[[x + yyn]] == x && x != yyterror_
&& !yy_table_value_is_error_ (yytable_[[x + yyn]]))
++count;
if (count < 5)
{
count = 0;
for (int x = yyxbegin; x < yyxend; ++x)
if (yycheck_[[x + yyn]] == x && x != yyterror_
&& !yy_table_value_is_error_ (yytable_[[x + yyn]]))
{
res.append (count++ == 0 ? ", expecting " : " or ");
res.append (yytnamerr_ (yytname_[[x]]));
}
}
}
return res.toString ();
}
}
return "syntax error";
}
/**
* Whether the given <code>yypact_</code> value indicates a defaulted state.
* @@param yyvalue the value to check
*/
private static boolean yy_pact_value_is_default_ (int yyvalue)
{
return yyvalue == yypact_ninf_;
}
/**
* Whether the given <code>yytable_</code> value indicates a syntax error.
* @@param yyvalue the value to check
*/
private static boolean yy_table_value_is_error_ (int yyvalue)
{
return yyvalue == yytable_ninf_;
}
/* YYPACT[[STATE-NUM]] -- Index in YYTABLE of the portion describing
STATE-NUM. */
private static final b4_int_type_for([b4_pact]) yypact_ninf_ = b4_pact_ninf;
private static final b4_int_type_for([b4_pact]) yypact_[[]] =
{
b4_pact
};
/* YYDEFACT[[S]] -- default reduction number in state S. Performed when
YYTABLE doesn't specify something else to do. Zero means the
default is an error. */
private static final b4_int_type_for([b4_defact]) yydefact_[[]] =
{
b4_defact
};
/* YYPGOTO[[NTERM-NUM]]. */
private static final b4_int_type_for([b4_pgoto]) yypgoto_[[]] =
{
b4_pgoto
};
/* YYDEFGOTO[[NTERM-NUM]]. */
private static final b4_int_type_for([b4_defgoto])
yydefgoto_[[]] =
{
b4_defgoto
};
/* YYTABLE[[YYPACT[STATE-NUM]]]. What to do in state STATE-NUM. If
positive, shift that token. If negative, reduce the rule which
number is the opposite. If YYTABLE_NINF_, syntax error. */
private static final b4_int_type_for([b4_table]) yytable_ninf_ =
b4_table_ninf;
private static final b4_int_type_for([b4_table])
yytable_[[]] =
{
b4_table
};
/* YYCHECK. */
private static final b4_int_type_for([b4_check])
yycheck_[[]] =
{
b4_check
};
/* STOS_[[STATE-NUM]] -- The (internal number of the) accessing
symbol of state STATE-NUM. */
private static final b4_int_type_for([b4_stos])
yystos_[[]] =
{
b4_stos
};
/* TOKEN_NUMBER_[[YYLEX-NUM]] -- Internal symbol number corresponding
to YYLEX-NUM. */
private static final b4_int_type_for([b4_toknum])
yytoken_number_[[]] =
{
b4_toknum
};
/* YYR1[[YYN]] -- Symbol number of symbol that rule YYN derives. */
private static final b4_int_type_for([b4_r1])
yyr1_[[]] =
{
b4_r1
};
/* YYR2[[YYN]] -- Number of symbols composing right hand side of rule YYN. */
private static final b4_int_type_for([b4_r2])
yyr2_[[]] =
{
b4_r2
};
/* YYTNAME[[SYMBOL-NUM]] -- String name of the symbol SYMBOL-NUM.
First, the terminals, then, starting at \a yyntokens_, nonterminals. */
private static final String yytname_[[]] =
{
b4_tname
};
/* YYRHS -- A `-1'-separated list of the rules' RHS. */
private static final b4_int_type_for([b4_rhs]) yyrhs_[[]] =
{
b4_rhs
};
/* YYPRHS[[YYN]] -- Index of the first RHS symbol of rule number YYN in
YYRHS. */
private static final b4_int_type_for([b4_prhs]) yyprhs_[[]] =
{
b4_prhs
};
/* YYRLINE[[YYN]] -- Source line where rule number YYN was defined. */
private static final b4_int_type_for([b4_rline]) yyrline_[[]] =
{
b4_rline
};
// Report on the debug stream that the rule yyrule is going to be reduced.
private void yy_reduce_print (int yyrule, YYStack yystack)
{
if (yydebug == 0)
return;
int yylno = yyrline_[[yyrule]];
int yynrhs = yyr2_[[yyrule]];
/* Print the symbols being reduced, and their result. */
yycdebug ("Reducing stack by rule " + (yyrule - 1)
+ " (line " + yylno + "), ");
/* The symbols being reduced. */
for (int yyi = 0; yyi < yynrhs; yyi++)
yy_symbol_print (" $" + (yyi + 1) + " =",
yyrhs_[[yyprhs_[yyrule] + yyi]],
b4_rhs_value(yynrhs, yyi + 1)b4_locations_if([,
b4_rhs_location(yynrhs, yyi + 1)]));
}
/* YYTRANSLATE(YYLEX) -- Bison symbol number corresponding to YYLEX. */
private static final b4_int_type_for([b4_translate]) yytranslate_table_[[]] =
{
b4_translate
};
private static final b4_int_type_for([b4_translate]) yytranslate_ (int t)
{
if (t >= 0 && t <= yyuser_token_number_max_)
return yytranslate_table_[[t]];
else
return yyundef_token_;
}
private static final int yylast_ = b4_last;
private static final int yynnts_ = b4_nterms_number;
private static final int yyempty_ = -2;
private static final int yyfinal_ = b4_final_state_number;
private static final int yyterror_ = 1;
private static final int yyerrcode_ = 256;
private static final int yyntokens_ = b4_tokens_number;
private static final int yyuser_token_number_max_ = b4_user_token_number_max;
private static final int yyundef_token_ = b4_undef_token_number;
/* User implementation code. */
b4_percent_code_get[]dnl
}
b4_epilogue
m4_divert_pop(0)dnl
# Checking Push Parsing. -*- Autotest -*-
# Copyright (C) 2007, 2009-2012 Free Software Foundation, Inc.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
AT_BANNER([[Java Push Parsing Tests]])
AT_SETUP([Trivial Push Parser])
AT_BISON_OPTION_PUSHDEFS
AT_DATA([[input.y]],
[
%language "Java"
%define parser_class_name "YYParser"
%define api.push-pull push
%code imports {
import java.io.*;
import java.util.*;
}
%%
start: 'a' 'b' 'c' ;
%%
public class Main
{
static public void main (String[[]] argv) throws IOException
{
YYParser parser;
parser = new YYParser();
assert (parser.push_parse('a', null) == YYParser.YYMORE);
parser = new YYParser();
assert (parser.push_parse('a', null) == YYParser.YYMORE);
assert (parser.push_parse('b', null) == YYParser.YYMORE);
assert (parser.push_parse('c', null) == YYParser.YYMORE);
assert (parser.push_parse('\0', null) == YYParser.YYACCEPT);
System.exit(0);
}
}
])
AT_BISON_OPTION_POPDEFS
AT_BISON_CHECK([[-S d:/lx.java -o Main.java input.y]])
AT_JAVA_COMPILE([[Main.java]])
AT_JAVA_PARSER_CHECK([Main], 0, [], [stderr])
AT_CLEANUP
AT_SETUP([Calc as a Push Parser])
AT_BISON_OPTION_PUSHDEFS
AT_DATA([Calc.y],
[/* Infix notation calculator--calc */
%language "Java"
%name-prefix "Calc"
%define parser_class_name "Calc"
%lex-param { Reader rdr}
%define api.push-pull both
%locations
%code imports {
import java.io.*;
}
%code lexer {
StreamTokenizer st;
public YYLexer(Reader rdr)
{
st = new StreamTokenizer(rdr);
st.resetSyntax();
st.eolIsSignificant(true);
st.whitespaceChars(9, 9);
st.whitespaceChars(32, 32);
st.wordChars(48, 57);
}
Position yypos = new Position (1, 0);
public Position getStartPos() {
return yypos;
}
public Position getEndPos() {
return yypos;
}
Integer yylval;
public Object getLVal() {
return yylval;
}
public void yyerror(Location loc, String msg)
{
System.err.println(loc+":"+msg);
}
public int yylex () throws IOException {
int ttype = st.nextToken ();
yypos = new Position (yypos.lineno (),yypos.token () + 1);
if (ttype == st.TT_EOF)
return Calc.EOF;
else if (ttype == st.TT_EOL)
{
yypos = new Position (yypos.lineno () + 1, 0);
return (int) '\n';
}
else if (ttype == st.TT_WORD)
{
yylval = new Integer (st.sval);
return Calc.NUM;
}
else
return st.ttype;
}
}
%code {
class Position {
public int line;
public int token;
public Position ()
{
line = 0;
token = 0;
}
public Position (int l, int t)
{
line = l;
token = t;
}
public boolean equals (Position l)
{
return l.line == line && l.token == token;
}
public String toString ()
{
return Integer.toString (line) + "." + Integer.toString(token);
}
public int lineno ()
{
return line;
}
public int token ()
{
return token;
}
}
public static void main (String[[]] argv)
throws IOException
{
String input = getinput(argv[[0]]);
StringReader reader = new StringReader(input);
Calc calc = new Calc(reader);
calc.setDebugLevel(1);
calc.parse();
}
static String
getinput(String filename)
throws IOException
{
StringBuilder buf = new StringBuilder();
FileReader file = new FileReader(filename);
int c;
while((c=file.read()) > 0) {
buf.append((char)c);
}
return buf.toString();
}
}
/* Bison Declarations */
%token <Integer> NUM "number"
%type <Integer> exp
%nonassoc '=' /* comparison */
%left '-' '+'
%left '*' '/'
%left NEG /* negation--unary minus */
%right '^' /* exponentiation */
/* Grammar follows */
%%
input:
line
| input line
;
line:
'\n'
| exp '\n'
| error '\n'
;
exp:
NUM { $[]$ = $[]1;}
| exp '=' exp
{
if ($[]1.intValue() != $[]3.intValue())
yyerror (]AT_LOCATION_IF(address@hidden,]])[ "calc: error: " + $[]1 + "
!= " + $[]3);
}
| exp '+' exp { $[]$ = new Integer ($[]1.intValue () + $[]3.intValue
()); }
| exp '-' exp { $[]$ = new Integer ($[]1.intValue () - $[]3.intValue
()); }
| exp '*' exp { $[]$ = new Integer ($[]1.intValue () * $[]3.intValue
()); }
| exp '/' exp { $[]$ = new Integer ($[]1.intValue () / $[]3.intValue
()); }
| '-' exp %prec NEG { $[]$ = new Integer (-$[]2.intValue ());
}
| exp '^' exp { $[]$ = new Integer ((int)
Math.pow ($[]1.intValue (),
$[]3.intValue ())); }
| '(' exp ')' { $[]$ = $[]2;
}
| '(' error ')' { $[]$ = new Integer (1111);}
| '!' { $[]$ = new Integer (0); return YYERROR;}
| '-' error { $[]$ = new Integer (0); return YYERROR;}
;
])
AT_BISON_OPTION_POPDEFS
AT_BISON_CHECK([[-S d:/lx.java -o Calc.java Calc.y]])
AT_JAVA_COMPILE([[Calc.java]])
AT_DATA([[input]],
[[1 + 2 * 3 = 7
1 + 2 * -3 = -5
-1^2 = -1
(-1)^2 = 1
---1 = -1
1 - 2 - 3 = -4
1 - (2 - 3) = 2
2^2^3 = 256
(2^2)^3 = 64
]])
AT_JAVA_PARSER_CHECK([Calc input], 0, [], [stderr])
AT_CLEANUP
- Push parsing for java...,
Dennis Heimbigner <=