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Calc.java
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import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;
public class Calc extends Object{
private static final boolean yydebug = false;
private static final class YYStack {
private static final class Ele {
public final int state;
public final int sval;
public Ele(int state, int sval) {
this.state = state;
this.sval = sval;
}
}
private final java.util.List stack;
public YYStack() {
stack = new java.util.ArrayList();
}
public void push(int state) {
stack.add(new Ele(state, 0));
}
public void push(int state, int sval) {
stack.add(new Ele(state, sval));
}
public void pop(int cnt) {
int size = stack.size();
stack.subList(size-cnt, size).clear();
}
public int peek(int idx) {
return ((Ele)stack.get(stack.size()-1-idx)).sval;
}
public int top() {
return ((Ele)stack.get(stack.size()-1)).state;
}
}
private final static class YYSVal {
public int val;
}
StreamTokenizer tok;
private Calc(InputStream in) {
tok = new StreamTokenizer(new InputStreamReader(in));
tok.eolIsSignificant(true);
tok.ordinaryChar('-');
}
public static void main(String[] args) {
Calc calc = new Calc(System.in);
calc.parse();
}
private int nextToken(YYSVal val) {
try {
int token = tok.nextToken();
switch(token) {
case StreamTokenizer.TT_NUMBER:
val.val = Math.round((float)tok.nval);
return NUM;
case '+':
case '-':
case '*':
case '/':
case '(':
case ')':
return token;
case StreamTokenizer.TT_EOL:
return RET;
case StreamTokenizer.TT_EOF:
return 0;
case StreamTokenizer.TT_WORD:
error("Unknown Token: " + tok.sval);
}
}
catch(java.io.IOException e) {
error(e.toString());
}
return 0;
}
void error(String msg) {
System.err.println(msg);
System.exit(1);
}
public static final int NUM = 256;
public static final int RET = 257;
private static final int YYINTERN = 258;
private static final String[] yyterms = {
"EOF",
"NUM", "RET", "'+'", "'-'", "'*'", "'/'", "'('", "')'",
};
private static final short[] yyintern = {
0, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
7, 8, 5, 3, 258, 4, 258, 6,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
258, 258, 258, 258, 258, 258, 258, 258,
1, 2,
};
private static final String[] yyrules = {
" 0: [ 0] $ -> eqs",
" 1: [ 1] eqs -> eqs eq RET",
" 2: [ 1] eqs ->",
" 3: [ 0] eq -> expr",
" 4: [ 1] expr -> NUM",
" 5: [ 0] expr -> '(' expr ')'",
" 6: [ 2] expr -> expr '+' expr",
" 7: [ 2] expr -> expr '-' expr",
" 8: [ 3] expr -> expr '*' expr",
" 9: [ 3] expr -> expr '/' expr",
};
private static final short[] yylength = {
1, 3, 0, 1, 1, 3, 3, 3,
3, 3,
};
private static final short[] yylhs = {
~0, 0, 0, 1, 2, 2, 2, 2,
2, 2,
};
private static final short[][] yygoto = {
{ 1, 0, 0, },
{ 0, 3, 2, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 6, },
{ 0, 0, 0, },
{ 0, 0, 15, },
{ 0, 0, 14, },
{ 0, 0, 13, },
{ 0, 0, 12, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 0, },
{ 0, 0, 0, },
};
private static final short[][] yyaction = {
{ -2, -2, 0, 0, 0, 0, 0, -2, 0, },
{ 1, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 0, -3, 7, 8, 9, 10, 0, 0, },
{ 0, 0, 16, 0, 0, 0, 0, 0, 0, },
{ 0, 0, -4, -4, -4, -4, -4, 0, -4, },
{ 0, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 0, 0, 7, 8, 9, 10, 0, 11, },
{ 0, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 4, 0, 0, 0, 0, 0, 5, 0, },
{ 0, 0, -5, -5, -5, -5, -5, 0, -5, },
{ 0, 0, -9, -9, -9, -9, -9, 0, -9, },
{ 0, 0, -8, -8, -8, -8, -8, 0, -8, },
{ 0, 0, -7, -7, -7, 9, 10, 0, -7, },
{ 0, 0, -6, -6, -6, 9, 10, 0, -6, },
{ -1, -1, 0, 0, 0, 0, 0, -1, 0, },
};
public void parse() {
YYStack yystack = new YYStack();
yystack.push(0);
// Fetch until error (throw) or accept (return)
while(true) {
// Current lookahead
YYSVal yysval = new YYSVal();
int yytok = nextToken(yysval);
if(yytok < YYINTERN) yytok = yyintern[yytok];
if(yytok >= YYINTERN) error("Unknown Token");
if(yydebug) {
System.err.println("Read " + yyterms[yytok]);
}
// Reduce until shift
while(true) {
final short yyact = yyaction[yystack.top()][yytok];
if(yyact == 0) error("Syntax Error");
if(yyact > 1) { // shift
if(yydebug) {
System.err.println("Push " + yyterms[yytok]);
}
yystack.push(yyact, yysval.val);
break;
}
else { // reduce (includes accept)
int yylval = 0;
final int yyrno = (yyact < 0)? -yyact : 0;
final int yylen = yylength[yyrno];
if(yydebug) {
System.err.println("Reduce by " + yyrules[yyrno]);
}
switch(yyrno) { // do semantic actions
case 0: // accept
return;
case 3: {
// Single Equation
System.out.println("= " + yystack.peek(yylen - 1));
break;
}
case 4: {
yylval = yystack.peek(yylen - 1);
break;
}
case 5: {
yylval = yystack.peek(yylen - 2);
break;
}
case 6: {
yylval = yystack.peek(yylen - 1) + yystack.peek(yylen - 3);
break;
}
case 7: {
yylval = yystack.peek(yylen - 1) - yystack.peek(yylen - 3);
break;
}
case 8: {
yylval = yystack.peek(yylen - 1) * yystack.peek(yylen - 3);
break;
}
case 9: {
yylval = yystack.peek(yylen - 1) / yystack.peek(yylen - 3);
break;
}
}
yystack.pop(yylen);
yystack.push(yygoto[yystack.top()][yylhs[yyrno]], yylval);
}
}
}
}
}