Lecture 10 YACC – Yet Another Compiler Compiler Introduction to YACC and Bison Topics Topics Yacc/Bison Introduction Readings: Readings: February 13, 2006 CSCE 531 Compiler Construction
Lecture 10 YACC – Yet Another Compiler Compiler Introduction to YACC and Bison Topics Yacc/Bison IntroductionReadings: February 13, 2006 CSCE 531 Compiler.
Dec 19, 2015
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Lecture 10 YACC – Yet Another Compiler Compiler
Introduction to YACC and Bison
Lecture 10 YACC – Yet Another Compiler Compiler
Introduction to YACC and Bison
Topics Topics Yacc/Bison Introduction
Readings:Readings:
February 13, 2006
CSCE 531 Compiler Construction
– 2 – CSCE 531 Spring 2006
OverviewOverviewLast TimeLast Time
Test 1 Post Mortem Lexical Analysis
Hash tableToken / Lexeme / Token Code
Review of LR Parsing
Today’s Lecture Today’s Lecture YACC introduction
References: References:
Homework: write a YACC specification for the language Homework: write a YACC specification for the language “core”“core”
– 3 – CSCE 531 Spring 2006
YACC Generated LALR(1) ParsersYACC Generated LALR(1) Parsers% flex lang.l% flex lang.l // lex.yy.c// lex.yy.c
% bison lang.y % bison lang.y // lang.c// lang.c
% gcc lex.yy.c lang.c –o parse% gcc lex.yy.c lang.c –o parse
% parse input% parse input
lang.y
lang.l FLEXlex.yy.cyylex()
lang.cyyparse()
BISON
Input source program
Executable Program
– 4 – CSCE 531 Spring 2006
YACC Format and UsageYACC Format and Usage
Yet Another Compiler Compiler Stephen Johnson 1976Yet Another Compiler Compiler Stephen Johnson 1976
Takes grammar specification and generates the Takes grammar specification and generates the Action and GOTO tablesAction and GOTO tables
Bison = new and improved YACCBison = new and improved YACC
YACC FormatYACC Format
Definitions sectionDefinitions section
%%%%
productions / semantic actions sectionproductions / semantic actions section
%%%%
routinesroutines
– 5 – CSCE 531 Spring 2006
Simple0.y in web/Examples/SimpleYaccSimple0.y in web/Examples/SimpleYacc
%token DIGIT%token DIGIT
%%%%
line : expr '\n' line : expr '\n'
;;
expr : expr '+' term expr : expr '+' term
| term| term
;;
term : term '*' factor term : term '*' factor
| factor| factor
;;
factor : '(' expr ')' factor : '(' expr ')'
| DIGIT| DIGIT
;;
%%%%
Grammar Grammar Bison Specification Bison Specification
expr expr expr '+' term | term expr '+' term | term
term term term '*' factor | factor term '*' factor | factor
factor factor '(' expr ')' | DIGIT '(' expr ')' | DIGIT
We first augment withWe first augment with
line line expr ‘\n’ expr ‘\n’
– 6 – CSCE 531 Spring 2006
Bison Specification File ExampleBison Specification File Example
deneb> more simple1.ydeneb> more simple1.y
%token DIGIT%token DIGIT
%%%%
expr : expr '+' expr expr : expr '+' expr
| expr '*' expr | expr '*' expr
| '(' expr ')' | '(' expr ')'
| DIGIT| DIGIT
;;
%%%%
– 7 – CSCE 531 Spring 2006
Bison Reporting ConflictsBison Reporting Conflicts
deneb> bison simple1.ydeneb> bison simple1.y
simple1.y contains 4 shift/reduce conflicts.simple1.y contains 4 shift/reduce conflicts.
bison -v simple1.ybison -v simple1.y
simple1.y contains 4 shift/reduce conflicts.simple1.y contains 4 shift/reduce conflicts.
So what are they?So what are they?
The “.output file” contains a description of the state The “.output file” contains a description of the state machine and actions.machine and actions.
– 8 – CSCE 531 Spring 2006
.output.output
deneb> more simple1.output deneb> more simple1.output
State 8 contains 2 shift/reduce conflicts.State 8 contains 2 shift/reduce conflicts.
State 9 contains 2 shift/reduce conflicts.State 9 contains 2 shift/reduce conflicts.
GrammarGrammar
Number, Line, RuleNumber, Line, Rule
1 5 expr -> expr '+' expr1 5 expr -> expr '+' expr
2 6 expr -> expr '*' expr2 6 expr -> expr '*' expr
3 7 expr -> '(' expr ')'3 7 expr -> '(' expr ')'
4 8 expr -> DIGIT4 8 expr -> DIGIT
– 9 – CSCE 531 Spring 2006
Terminals, with rules where they appearTerminals, with rules where they appear
$ $ (-1)(-1)
'(' '(' (40) 3(40) 3
')' ')' (41) 3(41) 3
'*' '*' (42) 2(42) 2
'+' '+' (43) 1(43) 1
error error (256)(256)
DIGIT DIGIT (257) (257) 44
Nonterminals, with rules where they appearNonterminals, with rules where they appear
expr (8)expr (8)
on left: 1 2 3 4, on right: 1 2 3on left: 1 2 3 4, on right: 1 2 3
– 10 – CSCE 531 Spring 2006
state 0state 0
DIGIT shift, and go to state 1DIGIT shift, and go to state 1
'(' shift, and go to state 2'(' shift, and go to state 2
expr go to state 3expr go to state 3
state 1state 1
expr -> DIGIT . (rule 4)expr -> DIGIT . (rule 4)
$default reduce using rule 4 (expr)$default reduce using rule 4 (expr)
– 11 – CSCE 531 Spring 2006
state 2state 2
expr -> '(' . expr ')' (rule 3)expr -> '(' . expr ')' (rule 3)
DIGIT shift, and go to state 1DIGIT shift, and go to state 1
'(' shift, and go to state 2'(' shift, and go to state 2
expr go to stateexpr go to state
– 12 – CSCE 531 Spring 2006
state 3state 3
expr -> expr . '+' expr (rule 1)expr -> expr . '+' expr (rule 1)
expr -> expr . '*' expr (rule 2)expr -> expr . '*' expr (rule 2)
$ go to state 10$ go to state 10
'+' shift, and go to state 5'+' shift, and go to state 5
'*' shift, and go to state 6'*' shift, and go to state 6
… … for states 4 through 7for states 4 through 7
– 13 – CSCE 531 Spring 2006
ConflictsConflictsstate 8state 8
expr -> expr . '+' expr (rule 1)expr -> expr . '+' expr (rule 1)
expr -> expr '+' expr . (rule 1)expr -> expr '+' expr . (rule 1)
expr -> expr . '*' expr (rule 2)expr -> expr . '*' expr (rule 2)
'+' shift, and go to state 5'+' shift, and go to state 5
'*' shift, and go to state 6'*' shift, and go to state 6
'+' [reduce using rule 1 (expr)]'+' [reduce using rule 1 (expr)]
'*' [reduce using rule 1 (expr)]'*' [reduce using rule 1 (expr)]
$default reduce using rule 1 (expr)$default reduce using rule 1 (expr)
– 14 – CSCE 531 Spring 2006
state 10state 10
$ go to state 11$ go to state 11
state 11state 11
$default accept$default accept
– 15 – CSCE 531 Spring 2006
Main and yyerrorMain and yyerror
– 16 – CSCE 531 Spring 2006
bison simple0.ybison simple0.y
deneb> deneb>
deneb> ls -lrtdeneb> ls -lrt
……
--rw-r--r-- 1 matthews faculty 28499 Jun 30 12:04 simple0.tab.crw-r--r-- 1 matthews faculty 28499 Jun 30 12:04 simple0.tab.c
deneb> wc simple0.tab.c deneb> wc simple0.tab.c
1084 4111 28499 simple0.tab.c1084 4111 28499 simple0.tab.c
– 17 – CSCE 531 Spring 2006
gcc simple0.tab.c -lygcc simple0.tab.c -ly
Undefined first referencedUndefined first referenced
symbol in filesymbol in file
yylex /var/tmp//ccW88jE5.oyylex /var/tmp//ccW88jE5.o
ld: fatal: Symbol referencing errors. No output written to ld: fatal: Symbol referencing errors. No output written to a.outa.out
collect2: ld returned 1 exit statuscollect2: ld returned 1 exit status
– 18 – CSCE 531 Spring 2006
deneb> more simple1.ydeneb> more simple1.y
%token DIGIT%token DIGIT
%%%%
expr : expr '+' expr expr : expr '+' expr
| expr '*' expr | expr '*' expr
| '(' expr ')' | '(' expr ')'
| DIGIT| DIGIT
;;
%%%%
– 19 – CSCE 531 Spring 2006
deneb> bison simple1.ydeneb> bison simple1.y
simple1.y contains 4 shift/reduce conflicts.simple1.y contains 4 shift/reduce conflicts.
bison -v simple1.ybison -v simple1.y
simple1.y contains 4 shift/reduce conflicts.simple1.y contains 4 shift/reduce conflicts.
deneb> ls -lrtdeneb> ls -lrt
……
--rw-r--r-- 1 matthews faculty 2311 Jun 30 12:10 simple1.outputrw-r--r-- 1 matthews faculty 2311 Jun 30 12:10 simple1.output
– 20 – CSCE 531 Spring 2006
.output.output
deneb> more simple1.output deneb> more simple1.output
State 8 contains 2 shift/reduce conflicts.State 8 contains 2 shift/reduce conflicts.
State 9 contains 2 shift/reduce conflicts.State 9 contains 2 shift/reduce conflicts.
GrammarGrammar
Number, Line, RuleNumber, Line, Rule
1 5 expr -> expr '+' expr1 5 expr -> expr '+' expr
2 6 expr -> expr '*' expr2 6 expr -> expr '*' expr
3 7 expr -> '(' expr ')'3 7 expr -> '(' expr ')'
4 8 expr -> DIGIT4 8 expr -> DIGIT
– 21 – CSCE 531 Spring 2006
Terminals, with rules where they appearTerminals, with rules where they appear
$ (-1)$ (-1)
'(' (40) 3'(' (40) 3
')' (41) 3')' (41) 3
'*' (42) 2'*' (42) 2
'+' (43) 1'+' (43) 1
error (256)error (256)
DIGIT (257) 4DIGIT (257) 4
Nonterminals, with rules where they appearNonterminals, with rules where they appear
expr (8)expr (8)
on left: 1 2 3 4, on right: 1 2 3on left: 1 2 3 4, on right: 1 2 3
– 22 – CSCE 531 Spring 2006
state 0state 0
DIGIT shift, and go to state 1DIGIT shift, and go to state 1
'(' shift, and go to state 2'(' shift, and go to state 2
expr go to state 3expr go to state 3
state 1state 1
expr -> DIGIT . (rule 4)expr -> DIGIT . (rule 4)
$default reduce using rule 4 (expr)$default reduce using rule 4 (expr)
44
– 23 – CSCE 531 Spring 2006
state 2state 2
expr -> '(' . expr ')' (rule 3)expr -> '(' . expr ')' (rule 3)
DIGIT shift, and go to state 1DIGIT shift, and go to state 1
'(' shift, and go to state 2'(' shift, and go to state 2
expr go to stateexpr go to state
– 24 – CSCE 531 Spring 2006
state 3state 3
expr -> expr . '+' expr (rule 1)expr -> expr . '+' expr (rule 1)
expr -> expr . '*' expr (rule 2)expr -> expr . '*' expr (rule 2)
$ go to state 10$ go to state 10
'+' shift, and go to state 5'+' shift, and go to state 5
'*' shift, and go to state 6'*' shift, and go to state 6
… … for states 4 through 7for states 4 through 7
– 25 – CSCE 531 Spring 2006
ConflictsConflicts
state 8state 8
expr -> expr . '+' expr (rule 1)expr -> expr . '+' expr (rule 1)
expr -> expr '+' expr . (rule 1)expr -> expr '+' expr . (rule 1)
expr -> expr . '*' expr (rule 2)expr -> expr . '*' expr (rule 2)
'+' shift, and go to state 5'+' shift, and go to state 5
'*' shift, and go to state 6'*' shift, and go to state 6
'+' [reduce using rule 1 (expr)]'+' [reduce using rule 1 (expr)]
'*' [reduce using rule 1 (expr)]'*' [reduce using rule 1 (expr)]
$default reduce using rule 1 (expr)$default reduce using rule 1 (expr)
– 26 – CSCE 531 Spring 2006
state 9state 9
expr -> expr . '+' expr (rule 1)expr -> expr . '+' expr (rule 1)
expr -> expr . '*' expr (rule 2)expr -> expr . '*' expr (rule 2)
expr -> expr '*' expr . (rule 2)expr -> expr '*' expr . (rule 2)
'+' shift, and go to state 5'+' shift, and go to state 5
'*' shift, and go to state 6'*' shift, and go to state 6
'+' [reduce using rule 2 (expr)]'+' [reduce using rule 2 (expr)]
'*' [reduce using rule 2 (expr)]'*' [reduce using rule 2 (expr)]
$default reduce using rule 2 (expr)$default reduce using rule 2 (expr)
– 27 – CSCE 531 Spring 2006
state 10state 10
$ go to state 11$ go to state 11
state 11state 11
$default accept$default accept
– 28 – CSCE 531 Spring 2006
YACC Generated LALR(1) ParsersYACC Generated LALR(1) Parsers% flex lang.l% flex lang.l // lex.yy.c// lex.yy.c
% bison lang.y % bison lang.y // lang.c// lang.c
% gcc lex.yy.c lang.c –o parse% gcc lex.yy.c lang.c –o parse
% parse input% parse input
lang.y
lang.l FLEXlex.yy.cyylex()
lang.cyyparse()
BISON
Input source program
Executable Program
– 29 – CSCE 531 Spring 2006
man yaccman yaccNAMENAME
yacc - yet another compiler-compileryacc - yet another compiler-compiler
SYNOPSISSYNOPSIS
yacc [-dltVv] [-b file_prefix] [ -Q [y | n] ] [-P parser] [-p sym_prefix] fileyacc [-dltVv] [-b file_prefix] [ -Q [y | n] ] [-P parser] [-p sym_prefix] file
DESCRIPTIONDESCRIPTION
The yacc command converts a context-free grammar into a set of The yacc command converts a context-free grammar into a set of tables for a simple automaton that executes an LALR(1) parsing tables for a simple automaton that executes an LALR(1) parsing algorithm. The grammar may be ambiguous. Specified precedence algorithm. The grammar may be ambiguous. Specified precedence rules are used to break ambiguities.rules are used to break ambiguities.
The output file, y.tab.c, must be compiled by the C compiler to The output file, y.tab.c, must be compiled by the C compiler to produce a function yyparse(). This program must be loaded with the produce a function yyparse(). This program must be loaded with the lexical analyzer program, yylex(), as well as main() and yyerror(), lexical analyzer program, yylex(), as well as main() and yyerror(), an error handling routine. These routines must be supplied by the an error handling routine. These routines must be supplied by the user. user.
– 30 – CSCE 531 Spring 2006
Bison Arguments: Bison –h Bison Arguments: Bison –h deneb> bison -hdeneb> bison -h
GNU bison generates parsers for LALR(1) grammars.GNU bison generates parsers for LALR(1) grammars.
Usage: bison [OPTION]... FILEUsage: bison [OPTION]... FILE
If a long option shows an argument as mandatory, then it is If a long option shows an argument as mandatory, then it is mandatorymandatory
for the equivalent short option also. Similarly for optional for the equivalent short option also. Similarly for optional arguments.arguments.
Operation modes:Operation modes:
-h, --help display this help and exit-h, --help display this help and exit
-V, --version output version information and exit-V, --version output version information and exit
-y, --yacc emulate POSIX yacc-y, --yacc emulate POSIX yacc
– 31 – CSCE 531 Spring 2006
Bison Arguments continuedBison Arguments continued
Output:Output:
-d, --defines also produce a header file-d, --defines also produce a header file
-v, --verbose -v, --verbose also produce an explanation of the automatonalso produce an explanation of the automaton
-b, --file-prefix=PREFIX specify a PREFIX for output files-b, --file-prefix=PREFIX specify a PREFIX for output files
-o, --output=FILE leave output to FILE-o, --output=FILE leave output to FILE
-g, --graph -g, --graph also produce a VCG description of the also produce a VCG description of the automatonautomaton
Report bugs to <[email protected]>.Report bugs to <[email protected]>.
deneb> deneb>
– 32 – CSCE 531 Spring 2006
Bison Arguments continuedBison Arguments continued
Parser:Parser:
-S, --skeleton=FILE specify the skeleton to use-S, --skeleton=FILE specify the skeleton to use
-t, --debug instrument the parser for -t, --debug instrument the parser for debuggingdebugging
--locations enable locations computation--locations enable locations computation
-p, --name-prefix=PREFIX prepend PREFIX to the -p, --name-prefix=PREFIX prepend PREFIX to the external symbolsexternal symbols
-l, --no-lines don't generate `#line' directives-l, --no-lines don't generate `#line' directives
-n, --no-parser generate the tables only-n, --no-parser generate the tables only
-k, --token-table include a table of token names-k, --token-table include a table of token names
– 33 – CSCE 531 Spring 2006
MakefilesMakefiles
A makefile is a file that specifies how to build A makefile is a file that specifies how to build something usually a piece of software something usually a piece of software
The makefile is a collection of targets with each target The makefile is a collection of targets with each target having a series of commands to build the targethaving a series of commands to build the target
To build the system one merely types “make”To build the system one merely types “make”
Make maintains dependencies and recompiles only Make maintains dependencies and recompiles only those files that need to be recompiledthose files that need to be recompiled
Make documents how to build a system and allows a Make documents how to build a system and allows a novice to install a piece of softwarenovice to install a piece of software
– 34 – CSCE 531 Spring 2006
MakefilesMakefiles
The makefile is a collection of targets with each target The makefile is a collection of targets with each target having a series of commands to build the targethaving a series of commands to build the target
The target specification has the formThe target specification has the form
targ: files that targ depends ontarg: files that targ depends on
<TAB>first unix command in a sequence to build target<TAB>first unix command in a sequence to build target
<TAB>next command in sequence to build target<TAB>next command in sequence to build target
<TAB> …<TAB> …
The Makefile specifies a forest of targets depending on The Makefile specifies a forest of targets depending on other targetsother targets
– 35 – CSCE 531 Spring 2006
Example MakefileExample Makefile
prog: prog.o routines.o prog: prog.o routines.o
prog.o: prog.c prog.hprog.o: prog.c prog.h
gcc –c prog.cgcc –c prog.c
routines.o: routines.c prog.hroutines.o: routines.c prog.h
gcc –c routines.cgcc –c routines.c
– 36 – CSCE 531 Spring 2006
Make Builtin RulesMake Builtin Rules
MacrosMacros
Name=valueName=value
$(Name)$(Name) //invocation of macro; replace //invocation of macro; replace macro macro with its value with its value
Suffixes: .c, .f, .y, .l …Suffixes: .c, .f, .y, .l …
Rules Rules
prog.o: prog.cprog.o: prog.c
$(CC) $(CFLAGS) –c prog.c$(CC) $(CFLAGS) –c prog.c
Actually the real rules are generalizations of the above.Actually the real rules are generalizations of the above.
Use “make –p” to see all the rules.Use “make –p” to see all the rules.
– 37 – CSCE 531 Spring 2006
/class/csce531-001/web/Examples/SimpleYacc/Makefile/class/csce531-001/web/Examples/SimpleYacc/Makefile
# Makefile for Simple Yacc and Lex examples # Makefile for Simple Yacc and Lex examples
CC=gccCC=gcc
CFLAGS=CFLAGS=
CFLAGS=-DYYDEBUGCFLAGS=-DYYDEBUG
LEX=flexLEX=flex
YACC=bisonYACC=bison
YACCFLAGS=YACCFLAGS=
YACCFLAGS=-t YACCFLAGS=-t
simple3: simple3.tab.h simple3.tab.o lex.yy.osimple3: simple3.tab.h simple3.tab.o lex.yy.o
$(CC) $(CFLAGS) simple3.tab.o lex.yy.o -ly -o simple3$(CC) $(CFLAGS) simple3.tab.o lex.yy.o -ly -o simple3
simple3.tab.h: simple3.ysimple3.tab.h: simple3.y
bison -d $(YACCFLAGS) simple3.ybison -d $(YACCFLAGS) simple3.y
simple3.tab.c: simple3.ysimple3.tab.c: simple3.y
bison $(YACCFLAGS) simple3.ybison $(YACCFLAGS) simple3.y
lex.yy.c: simple3.llex.yy.c: simple3.l
flex simple3.l flex simple3.l
– 38 – CSCE 531 Spring 2006
Lex Specification simple3.lLex Specification simple3.l%{%{
#include "simple0.tab.h"#include "simple0.tab.h"
%}%}
digit [0-9]+digit [0-9]+
%%%%
\n \n return('\n');return('\n');
\+ \+ return(PLUS);return(PLUS);
\* \* return(TIMES);return(TIMES);
\( \( return(LPAREN);return(LPAREN);
\) \) return(RPAREN);return(RPAREN);
{digit} return(DIGIT);{digit} return(DIGIT);
%%%%
yywrap(){yywrap(){
}}
– 39 – CSCE 531 Spring 2006
Example Yacc Spec file simple3.yExample Yacc Spec file simple3.y%token DIGIT TIMES PLUS LPAREN RPAREN%token DIGIT TIMES PLUS LPAREN RPAREN
%%%%
line : expr '\n' {printf("recognized an expr\n");line : expr '\n' {printf("recognized an expr\n");
exit(0);exit(0);
}}
;;
expr : expr PLUS term expr : expr PLUS term
| term| term
;;
term : term TIMES factor term : term TIMES factor
| factor| factor
;;
factor : LPAREN expr RPAREN factor : LPAREN expr RPAREN
| DIGIT| DIGIT
;;
%%%%
– 40 – CSCE 531 Spring 2006
Simple4.lSimple4.l%{%{
#include "simple4.tab.h"#include "simple4.tab.h"
%}%}
digit [0-9]+digit [0-9]+
%%%%
\n return('\n');\n return('\n');
\+ return(PLUS);\+ return(PLUS);
\* return(TIMES);\* return(TIMES);
\( return(LPAREN);\( return(LPAREN);
\) return(RPAREN);\) return(RPAREN);
{digit} { yylval= atoi(yytext); return(INTEGER);}{digit} { yylval= atoi(yytext); return(INTEGER);}
%%%%
yywrap(){ }yywrap(){ }
– 41 – CSCE 531 Spring 2006
Simple4.ySimple4.y%{%{
#include <ctype.h>#include <ctype.h>
int yylineno = 1;int yylineno = 1;
%}%}
%token INTEGER PLUS TIMES LPAREN RPAREN%token INTEGER PLUS TIMES LPAREN RPAREN
%%%%
line : expr '\n' {printf("%d\n", $1);}line : expr '\n' {printf("%d\n", $1);}
| line expr '\n' {printf("%d\n", $2);}| line expr '\n' {printf("%d\n", $2);}
;;
expr : expr PLUS term {$$ = $1 + $3;}expr : expr PLUS term {$$ = $1 + $3;}
| term| term
;;
term : term TIMES factor {$$ = $1 * $3;}term : term TIMES factor {$$ = $1 * $3;}
| factor| factor
;;
factor : LPAREN expr RPAREN {$$ = $2;}factor : LPAREN expr RPAREN {$$ = $2;}
| INTEGER {$$ = $1;} /* the default action */| INTEGER {$$ = $1;} /* the default action */
;;
%%%%
Related Documents
