/* Parser and scanner for calc in Java. -*- Java -*-
Copyright (C) 2018-2021 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
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 <https://www.gnu.org/licenses/>. */
%language "Java"
%define api.parser.class {Calc}
%define api.parser.public
%define api.push-pull push
// Customized syntax error messages (see reportSyntaxError)...
%define parse.error custom
// ... with locations...
%locations
// ... and accurate list of expected tokens.
%define parse.lac full
%define parse.trace
%code imports {
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.nio.CharBuffer;
}
%code {
public static void main(String[] args) throws IOException {
CalcLexer scanner = new CalcLexer(System.in);
Calc parser = new Calc(scanner);
for (String arg : args)
if (arg.equals("-p"))
parser.setDebugLevel(1);
int status;
do {
int token = scanner.getToken();
Object lval = scanner.getValue();
Calc.Location yyloc = scanner.getLocation();
status = parser.push_parse(token, lval, yyloc);
} while (status == Calc.YYPUSH_MORE);
if (status != Calc.YYACCEPT)
System.exit(1);
}
static String i18n(String s) {
return s;
}
}
/* Bison Declarations */
%token
BANG "!"
PLUS "+"
MINUS "-"
STAR "*"
SLASH "/"
CARET "^"
LPAREN "("
RPAREN ")"
EQUAL "="
EOL _("end of line")
<Integer>
NUM _("number")
%type <Integer> exp
%nonassoc "=" /* comparison */
%left "-" "+"
%left "*" "/"
%precedence NEG /* negation--unary minus */
%right "^" /* exponentiation */
/* Grammar follows */
%%
input:
line
| input line
;
line:
EOL
| exp EOL { System.out.println($exp); }
| error EOL
;
exp:
NUM { $$ = $1; }
| exp "=" exp
{
if ($1.intValue() != $3.intValue())
yyerror(@$, "calc: error: " + $1 + " != " + $3);
}
| exp "+" exp { $$ = $1 + $3; }
| exp "-" exp { $$ = $1 - $3; }
| exp "*" exp { $$ = $1 * $3; }
| exp "/" exp { $$ = $1 / $3; }
| "-" exp %prec NEG { $$ = -$2; }
| exp "^" exp { $$ = (int) Math.pow($1, $3); }
| "(" exp ")" { $$ = $2; }
| "(" error ")" { $$ = 1111; }
| "!" { $$ = 0; return YYERROR; }
| "-" error { $$ = 0; return YYERROR; }
;
%%
class CalcLexer implements Calc.Lexer {
StreamTokenizer st;
PositionReader reader;
public CalcLexer(InputStream is) {
reader = new PositionReader(new InputStreamReader(is));
st = new StreamTokenizer(reader);
st.resetSyntax();
st.eolIsSignificant(true);
st.wordChars('0', '9');
}
Position start = new Position(1, 0);
Position end = new Position(1, 0);
/**
* The location of the last token read.
* Implemented with getStartPos and getEndPos in pull parsers.
*/
public Calc.Location getLocation() {
return new Calc.Location(new Position(start), new Position(end));
}
/**
* Build and emit a syntax error message.
*/
public void reportSyntaxError(Calc.Context ctx) {
System.err.print(ctx.getLocation() + ": syntax error");
{
final int TOKENMAX = 10;
Calc.SymbolKind[] arg = new Calc.SymbolKind[TOKENMAX];
int n = ctx.getExpectedTokens(arg, TOKENMAX);
for (int i = 0; i < n; ++i)
System.err.print((i == 0 ? ": expected " : " or ")
+ arg[i].getName());
}
{
Calc.SymbolKind lookahead = ctx.getToken();
if (lookahead != null)
System.err.print(" before " + lookahead.getName());
}
System.err.println("");
}
/**
* Emit an error referring to the given location in a user-defined way.
*
* @@param loc The location of the element to which the
* error message is related.
* @@param msg The string for the error message.
*/
public void yyerror(Calc.Location loc, String msg) {
if (loc == null)
System.err.println(msg);
else
System.err.println(loc + ": " + msg);
}
Integer yylval;
/**
* The value of the last token read. Called getLVal in pull parsers.
*/
public Object getValue() {
return yylval;
}
/**
* Fetch the next token. Called yylex in pull parsers.
*/
public int getToken() throws IOException {
start.set(reader.getPosition());
int ttype = st.nextToken();
end.set(reader.getPosition());
switch (ttype) {
case StreamTokenizer.TT_EOF:
return YYEOF;
case StreamTokenizer.TT_EOL:
end.line += 1;
end.column = 0;
return EOL;
case StreamTokenizer.TT_WORD:
yylval = Integer.parseInt(st.sval);
end.set(reader.getPreviousPosition());
return NUM;
case ' ': case '\t':
return getToken();
case '!':
return BANG;
case '+':
return PLUS;
case '-':
return MINUS;
case '*':
return STAR;
case '/':
return SLASH;
case '^':
return CARET;
case '(':
return LPAREN;
case ')':
return RPAREN;
case '=':
return EQUAL;
default:
throw new AssertionError("invalid character: " + ttype);
}
}
}
/**
* A class defining a point in the input.
*/
class Position {
public int line = 1;
public int column = 1;
public Position() {
line = 1;
column = 1;
}
public Position(int l, int t) {
line = l;
column = t;
}
public Position(Position p) {
line = p.line;
column = p.column;
}
public void set(Position p) {
line = p.line;
column = p.column;
}
public boolean equals(Position l) {
return l.line == line && l.column == column;
}
public String toString() {
return Integer.toString(line) + "." + Integer.toString(column);
}
public int line() {
return line;
}
public int column() {
return column;
}
}
/**
* A Stream reader that keeps track of the current Position.
*/
class PositionReader extends BufferedReader {
private Position position = new Position();
// Position before the latest call to "read", i.e. position
// of the last character of the current token.
private Position previousPosition = new Position();
public PositionReader(Reader reader) {
super(reader);
}
public int read() throws IOException {
previousPosition.set(position);
int res = super.read();
if (res > -1) {
char c = (char) res;
if (c == '\r' || c == '\n') {
position.line += 1;
position.column = 1;
} else {
position.column += 1;
}
}
return res;
}
public Position getPosition() {
return position;
}
public Position getPreviousPosition() {
return previousPosition;
}
}
Generated by dwww version 1.15 on Sun Jun 16 17:07:09 CEST 2024.