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11027558c8
From
public interface Lexer {
/* Token kinds. */
/** Token number, to be returned by the scanner. */
static final int YYEOF = 0;
/** Token number, to be returned by the scanner. */
static final int YYERRCODE = 256;
/** Token number, to be returned by the scanner. */
static final int YYUNDEF = 257;
/** Token number, to be returned by the scanner. */
static final int BANG = 258;
...
/** Deprecated, use b4_symbol(0, id) instead. */
public static final int EOF = YYEOF;
to
public interface Lexer {
/* Token kinds. */
/** Token "end of file", to be returned by the scanner. */
static final int YYEOF = 0;
/** Token error, to be returned by the scanner. */
static final int YYerror = 256;
/** Token "invalid token", to be returned by the scanner. */
static final int YYUNDEF = 257;
/** Token "!", to be returned by the scanner. */
static final int BANG = 258;
...
/** Deprecated, use YYEOF instead. */
public static final int EOF = YYEOF;
* data/skeletons/java.m4 (b4_token_enum): Display the symbol's tag in
comment.
* data/skeletons/lalr1.java: Address overquotation issue.
* examples/java/calc/Calc.y, examples/java/simple/Calc.y: Use YYEOF,
not EOF.
107 lines
2.2 KiB
Plaintext
107 lines
2.2 KiB
Plaintext
%language "Java"
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%define api.parser.class {Calc}
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%define api.parser.public
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%define parse.error verbose
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%code imports {
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.Reader;
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import java.io.StreamTokenizer;
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}
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%code {
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public static void main(String[] args) throws IOException {
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CalcLexer l = new CalcLexer(System.in);
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Calc p = new Calc(l);
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if (!p.parse())
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System.exit(1);
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}
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}
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/* Bison Declarations */
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%token <Integer> NUM "number"
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%type <Integer> exp
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%nonassoc '=' /* comparison */
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%left '-' '+'
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%left '*' '/'
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%precedence NEG /* negation--unary minus */
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%right '^' /* exponentiation */
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/* Grammar follows */
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%%
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input:
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line
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| input line
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;
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line:
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'\n'
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| exp '\n' { System.out.println($exp); }
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| error '\n'
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;
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exp:
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NUM { $$ = $1; }
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| exp '=' exp
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{
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if ($1.intValue() != $3.intValue())
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yyerror("calc: error: " + $1 + " != " + $3);
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}
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| exp '+' exp { $$ = $1 + $3; }
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| exp '-' exp { $$ = $1 - $3; }
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| exp '*' exp { $$ = $1 * $3; }
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| exp '/' exp { $$ = $1 / $3; }
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| '-' exp %prec NEG { $$ = -$2; }
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| exp '^' exp { $$ = (int) Math.pow($1, $3); }
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| '(' exp ')' { $$ = $2; }
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| '(' error ')' { $$ = 1111; }
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| '!' { $$ = 0; return YYERROR; }
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| '-' error { $$ = 0; return YYERROR; }
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;
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%%
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class CalcLexer implements Calc.Lexer {
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StreamTokenizer st;
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public CalcLexer(InputStream is) {
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st = new StreamTokenizer(new InputStreamReader(is));
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st.resetSyntax();
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st.eolIsSignificant(true);
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st.whitespaceChars('\t', '\t');
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st.whitespaceChars(' ', ' ');
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st.wordChars('0', '9');
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}
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public void yyerror(String s) {
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System.err.println(s);
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}
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Integer yylval;
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public Object getLVal() {
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return yylval;
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}
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public int yylex() throws IOException {
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int ttype = st.nextToken();
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switch (ttype) {
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case StreamTokenizer.TT_EOF:
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return YYEOF;
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case StreamTokenizer.TT_EOL:
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return (int) '\n';
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case StreamTokenizer.TT_WORD:
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yylval = new Integer(st.sval);
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return NUM;
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default:
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return ttype;
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}
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}
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}
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