/
Parser.cs
674 lines (618 loc) · 16.2 KB
/
Parser.cs
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using System;
namespace Taste {
public class Parser {
public const int _EOF = 0;
public const int _ident = 1;
public const int _number = 2;
public const int _strT = 3;
public const int _charT = 4;
public const int maxT = 44;
const bool T = true;
const bool x = false;
const int minErrDist = 2;
public Scanner scanner;
public Errors errors;
public Token t; // last recognized token
public Token la; // lookahead token
int errDist = minErrDist;
const int // types
undef = 0, integer = 1, boolean = 2, str = 3;
const int // object kinds
var = 0, proc = 1, constant = 2;
public SymbolTable tab;
public CodeGenerator gen;
/*--------------------------------------------------------------------------*/
public Parser(Scanner scanner) {
this.scanner = scanner;
errors = new Errors();
}
void SynErr (int n) {
if (errDist >= minErrDist) errors.SynErr(la.line, la.col, n);
errDist = 0;
}
public void SemErr (string msg) {
if (errDist >= minErrDist) errors.SemErr(t.line, t.col, msg);
errDist = 0;
}
void Get () {
for (;;) {
t = la;
la = scanner.Scan();
if (la.kind <= maxT) { ++errDist; break; }
la = t;
}
}
void Expect (int n) {
if (la.kind==n) Get(); else { SynErr(n); }
}
bool StartOf (int s) {
return set[s, la.kind];
}
void ExpectWeak (int n, int follow) {
if (la.kind == n) Get();
else {
SynErr(n);
while (!StartOf(follow)) Get();
}
}
bool WeakSeparator(int n, int syFol, int repFol) {
int kind = la.kind;
if (kind == n) {Get(); return true;}
else if (StartOf(repFol)) {return false;}
else {
SynErr(n);
while (!(set[syFol, kind] || set[repFol, kind] || set[0, kind])) {
Get();
kind = la.kind;
}
return StartOf(syFol);
}
}
void AddOp(out Op op) {
op = Op.ADD;
if (la.kind == 5) {
Get();
} else if (la.kind == 6) {
Get();
op = Op.SUB;
} else SynErr(45);
}
void ConstDecl() {
Obj obj; int type; string name;
Expect(7);
Ident(out name);
Expect(8);
Expr(out type);
tab.NewObj(name, constant, type); obj = tab.Find(name);
if(obj.level==0) gen.Emit(Op.STOG, obj.adr);
else gen.Emit(Op.STO, obj.adr);
while (la.kind == 9) {
Get();
ConstDecl();
}
Expect(10);
}
void Ident(out string name) {
Expect(1);
name = t.val;
}
void Expr(out int type) {
int type1; Op op;
SimExpr(out type);
if (StartOf(1)) {
RelOp(out op);
SimExpr(out type1);
if (type != type1) SemErr("incompatible types");
gen.Emit(op); type = boolean;
}
}
void SimExpr(out int type) {
int type1; Op op;
Term(out type);
while (la.kind == 5 || la.kind == 6) {
AddOp(out op);
Term(out type1);
if (type != integer || type1 != integer)
SemErr("integer type expected");
gen.Emit(op);
}
}
void RelOp(out Op op) {
op = Op.EQU;
switch (la.kind) {
case 22: {
Get();
break;
}
case 23: {
Get();
op = Op.LSS;
break;
}
case 24: {
Get();
op = Op.GTR;
break;
}
case 25: {
Get();
op = Op.NEQ;
break;
}
case 26: {
Get();
op = Op.LSE;
break;
}
case 27: {
Get();
op = Op.GTE;
break;
}
default: SynErr(46); break;
}
}
void Factor(out int type) {
int n, adr; Obj obj; string name; string s;
type = undef;
switch (la.kind) {
case 11: {
Get();
Expr(out type);
Expect(12);
break;
}
case 1: {
Ident(out name);
obj = tab.Find(name); type = obj.type; adr = obj.adr;
if (la.kind == 13) {
Get();
if(!obj.isArray) SemErr("Not an array");
Expect(2);
n = Convert.ToInt32(t.val);
if( n > obj.size || n < 1) SemErr("Run-time exception - array index out of bounds");
else adr = adr + (n-1);
Expect(14);
} else if (StartOf(2)) {
if(obj.isArray) SemErr("Index of array missing");
} else SynErr(47);
if (obj.kind == var || obj.kind == constant) {
if (obj.level == 0) gen.Emit(Op.LOADG, adr);
else gen.Emit(Op.LOAD, adr);
} else SemErr("variable or constant expected");
break;
}
case 2: {
Get();
n = Convert.ToInt32(t.val);
gen.Emit(Op.CONST, n); type = integer;
break;
}
case 6: {
Get();
Factor(out type);
if (type != integer) {
SemErr("integer type expected"); type = integer;
}
gen.Emit(Op.NEG);
break;
}
case 15: {
Get();
gen.Emit(Op.CONST, 1); type = boolean;
break;
}
case 16: {
Get();
gen.Emit(Op.CONST, 0); type = boolean;
break;
}
case 3: {
Get();
s = Convert.ToString(t.val);
gen.Emit(Op.STR, s, s.Length); type = str;
break;
}
case 4: {
Get();
s = Convert.ToString(t.val);
gen.Emit(Op.STR, s, 3); type = str;
break;
}
default: SynErr(48); break;
}
}
void MulOp(out Op op) {
op = Op.MUL;
if (la.kind == 17) {
Get();
} else if (la.kind == 18) {
Get();
op = Op.DIV;
} else SynErr(49);
}
void ProcDecl() {
string name; Obj obj; int adr;
Expect(19);
Ident(out name);
obj = tab.NewObj(name, proc, undef); obj.adr = gen.pc;
if (name == "Main") gen.progStart = gen.pc;
tab.OpenScope();
Expect(11);
Expect(12);
Expect(20);
gen.Emit(Op.ENTER, 0); adr = gen.pc - 2;
while (StartOf(3)) {
if (la.kind == 7) {
ConstDecl();
} else if (StartOf(4)) {
VarDecl();
} else {
Stat();
}
}
Expect(21);
gen.Emit(Op.LEAVE); gen.Emit(Op.RET);
gen.Patch(adr, tab.topScope.nextAdr);
tab.CloseScope();
}
void VarDecl() {
string name; int type, n=0; Obj obj;
Type(out type);
Ident(out name);
tab.NewObj(name, var, type);
if (la.kind == 13) {
Get();
Expect(2);
n = Convert.ToInt32(t.val); if(type != integer) SemErr("integer type expected for array");
if(n<1) SemErr("Array size must be a positive integer");
tab.toArray(name, n); obj = tab.Find(name);
if(obj.level == 0) gen.Emit(Op.STOGA, obj.adr, n);
else gen.Emit(Op.STOA, obj.adr, n);
Expect(14);
}
while (la.kind == 9) {
Get();
Ident(out name);
tab.NewObj(name, var, type);
if (la.kind == 13) {
Get();
Expect(2);
n = Convert.ToInt32(t.val); if(type != integer) SemErr("integer type expected for array");
if(n<1) SemErr("Array size must be a positive integer");
tab.toArray(name, n); obj = tab.Find(name);
if(obj.level == 0) gen.Emit(Op.STOGA, obj.adr, n);
else gen.Emit(Op.STOA, obj.adr, n);
Expect(14);
}
}
Expect(10);
}
void Stat() {
int type; string name; Obj obj, obj1; int n;
int adr, adr2, adr3, loopstart;
switch (la.kind) {
case 1: {
Ident(out name);
obj = tab.Find(name); adr3 = obj.adr;
if (la.kind == 8 || la.kind == 13) {
if (la.kind == 13) {
Get();
if(!obj.isArray) SemErr("Identifier is not an array");
Expect(2);
n = Convert.ToInt32(t.val);
if( n > obj.size || n < 1) SemErr("Run-time exception - array index out of bounds");
else adr3 = adr3 + (n-1);
Expect(14);
} else {
if(obj.isArray) SemErr("Array missing index");
}
Expect(8);
if (obj.kind != var) SemErr("can only assign to variables");
Expr(out type);
if (la.kind == 28) {
Get();
if(type != boolean) SemErr("boolean type expected");
gen.Emit(Op.FJMP, 0); adr = gen.pc - 2;
Expr(out type);
if(type != obj.type) SemErr("incompatible types");
gen.Emit(Op.JMP, 0); adr2 = gen.pc - 2;
Expect(29);
gen.Patch(adr, gen.pc) ;
Expr(out type);
if(type != obj.type) SemErr("incompatible types");
gen.Patch(adr2, gen.pc);
} else if (la.kind == 10) {
if (type != obj.type) SemErr("incompatible types");
} else SynErr(50);
if (obj.level == 0) gen.Emit(Op.STOG, adr3);
else gen.Emit(Op.STO, adr3);
} else if (la.kind == 11) {
Get();
Expect(12);
if (obj.kind != proc) SemErr("object is not a procedure");
gen.Emit(Op.CALL, obj.adr);
} else SynErr(51);
Expect(10);
break;
}
case 30: {
Get();
Expect(11);
Expr(out type);
Expect(12);
if (type != boolean) SemErr("boolean type expected");
gen.Emit(Op.FJMP, 0); adr = gen.pc - 2;
Stat();
if (la.kind == 31) {
Get();
gen.Emit(Op.JMP, 0); adr2 = gen.pc - 2;
gen.Patch(adr, gen.pc);
adr = adr2;
Stat();
}
gen.Patch(adr, gen.pc);
break;
}
case 32: {
Get();
loopstart = gen.pc;
Expect(11);
Expr(out type);
Expect(12);
if (type != boolean) SemErr("boolean type expected");
gen.Emit(Op.FJMP, 0); adr = gen.pc - 2;
Stat();
gen.Emit(Op.JMP, loopstart); gen.Patch(adr, gen.pc);
break;
}
case 33: {
Get();
loopstart = gen.pc;
Stat();
Expect(32);
Expect(11);
Expr(out type);
Expect(34);
if (type != boolean) SemErr("boolean type expected");
gen.Emit(Op.FJMP, 0); adr = gen.pc - 2;
gen.Emit(Op.JMP, loopstart); gen.Patch(adr, gen.pc);
break;
}
case 35: {
Get();
Ident(out name);
Expect(10);
obj = tab.Find(name);
if (obj.type != integer) SemErr("integer type expected");
gen.Emit(Op.READ);
if (obj.level == 0) gen.Emit(Op.STOG, obj.adr);
else gen.Emit(Op.STO, obj.adr);
break;
}
case 36: {
Get();
Expr(out type);
if (type != integer && type != str) SemErr("integer or string type expected");
if(type == integer) gen.Emit(Op.WRITE);
else gen.Emit(Op.WRITES);
while (la.kind == 9) {
Get();
gen.Emit(Op.WRITEC);
Expr(out type);
if (type != integer && type != str) SemErr("integer or string type expected");
if(type == integer) gen.Emit(Op.WRITE);
else gen.Emit(Op.WRITES);
}
Expect(10);
gen.Emit(Op.WRITEL);
break;
}
case 20: {
Get();
while (StartOf(5)) {
if (StartOf(6)) {
Stat();
} else {
VarDecl();
}
}
Expect(21);
break;
}
case 37: {
Get();
Ident(out name);
obj = tab.Find(name); if(obj.kind != var && obj.type != integer) SemErr("integer variable needed in for loop");
Expect(8);
if (la.kind == 2) {
Get();
n = Convert.ToInt32(t.val);
gen.Emit(Op.CONST, n);
} else if (la.kind == 1) {
Ident(out name);
obj1 = tab.Find(name); if(obj1.kind != constant && obj1.type != integer) SemErr("integer constant expected");
if(obj1.level==0) gen.Emit(Op.LOADG, obj1.adr);
else gen.Emit(Op.LOAD, obj1.adr);
} else SynErr(52);
if(obj.level==0) gen.Emit(Op.STOG, obj.adr);
else gen.Emit(Op.STO, obj.adr);
loopstart = gen.pc;
if (obj.level == 0) gen.Emit(Op.LOADG, obj.adr);
else gen.Emit(Op.LOAD, obj.adr);
Expect(38);
if (la.kind == 2) {
Get();
n = Convert.ToInt32(t.val); type = integer;
gen.Emit(Op.CONST, n);
} else if (la.kind == 1) {
Ident(out name);
obj1 = tab.Find(name); if(obj1.kind != constant && obj1.type != integer) SemErr("integer constant expected");
if(obj1.level==0) gen.Emit(Op.LOADG, obj1.adr);
else gen.Emit(Op.LOAD, obj1.adr);
} else SynErr(53);
gen.Emit(Op.LSE); gen.Emit(Op.FJMP, 0); adr = gen.pc - 2;
Expect(33);
Stat();
if(obj.level==0) gen.Emit(Op.LOAD, obj.adr);
else gen.Emit(Op.LOADG, obj.adr);
gen.Emit(Op.CONST, 1); gen.Emit(Op.ADD);
if(obj.level==0) gen.Emit(Op.STOG, obj.adr);
else gen.Emit(Op.STO, obj.adr);
gen.Emit(Op.JMP, loopstart); gen.Patch(adr, gen.pc);
break;
}
default: SynErr(54); break;
}
}
void Term(out int type) {
int type1; Op op;
Factor(out type);
while (la.kind == 17 || la.kind == 18) {
MulOp(out op);
Factor(out type1);
if (type != integer || type1 != integer)
SemErr("integer type expected");
gen.Emit(op);
}
}
void Taste() {
string name;
Expect(39);
Ident(out name);
tab.OpenScope();
Expect(20);
while (StartOf(7)) {
if (la.kind == 7) {
ConstDecl();
} else if (StartOf(4)) {
VarDecl();
} else {
ProcDecl();
}
}
Expect(21);
tab.CloseScope();
if (gen.progStart == -1) SemErr("main function never defined");
}
void Type(out int type) {
type = undef;
if (la.kind == 40) {
Get();
type = integer;
} else if (la.kind == 41) {
Get();
type = boolean;
} else if (la.kind == 42) {
Get();
type = str;
} else if (la.kind == 43) {
Get();
type = str;
} else SynErr(55);
}
public void Parse() {
la = new Token();
la.val = "";
Get();
Taste();
Expect(0);
}
static readonly bool[,] set = {
{T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x},
{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,T,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x},
{x,x,x,x, x,T,T,x, x,T,T,x, T,x,x,x, x,T,T,x, x,x,T,T, T,T,T,T, T,T,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,x},
{x,T,x,x, x,x,x,T, x,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, x,x,x,x, x,x,T,x, T,T,x,T, T,T,x,x, T,T,T,T, x,x},
{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, x,x},
{x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, x,x,x,x, x,x,T,x, T,T,x,T, T,T,x,x, T,T,T,T, x,x},
{x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, x,x,x,x, x,x,T,x, T,T,x,T, T,T,x,x, x,x,x,x, x,x},
{x,x,x,x, x,x,x,T, x,x,x,x, x,x,x,x, x,x,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, x,x}
};
} // end Parser
public class Errors {
public int count = 0; // number of errors detected
public System.IO.TextWriter errorStream = Console.Out; // error messages go to this stream
public string errMsgFormat = "-- line {0} col {1}: {2}"; // 0=line, 1=column, 2=text
public virtual void SynErr (int line, int col, int n) {
string s;
switch (n) {
case 0: s = "EOF expected"; break;
case 1: s = "ident expected"; break;
case 2: s = "number expected"; break;
case 3: s = "strT expected"; break;
case 4: s = "charT expected"; break;
case 5: s = "\"+\" expected"; break;
case 6: s = "\"-\" expected"; break;
case 7: s = "\"constant\" expected"; break;
case 8: s = "\":=\" expected"; break;
case 9: s = "\",\" expected"; break;
case 10: s = "\";\" expected"; break;
case 11: s = "\"(\" expected"; break;
case 12: s = "\")\" expected"; break;
case 13: s = "\"[\" expected"; break;
case 14: s = "\"]\" expected"; break;
case 15: s = "\"true\" expected"; break;
case 16: s = "\"false\" expected"; break;
case 17: s = "\"*\" expected"; break;
case 18: s = "\"/\" expected"; break;
case 19: s = "\"void\" expected"; break;
case 20: s = "\"{\" expected"; break;
case 21: s = "\"}\" expected"; break;
case 22: s = "\"==\" expected"; break;
case 23: s = "\"<\" expected"; break;
case 24: s = "\">\" expected"; break;
case 25: s = "\"!=\" expected"; break;
case 26: s = "\"<=\" expected"; break;
case 27: s = "\">=\" expected"; break;
case 28: s = "\"?\" expected"; break;
case 29: s = "\":\" expected"; break;
case 30: s = "\"if\" expected"; break;
case 31: s = "\"else\" expected"; break;
case 32: s = "\"while\" expected"; break;
case 33: s = "\"do\" expected"; break;
case 34: s = "\");\" expected"; break;
case 35: s = "\"read\" expected"; break;
case 36: s = "\"write\" expected"; break;
case 37: s = "\"for\" expected"; break;
case 38: s = "\"to\" expected"; break;
case 39: s = "\"program\" expected"; break;
case 40: s = "\"int\" expected"; break;
case 41: s = "\"bool\" expected"; break;
case 42: s = "\"string\" expected"; break;
case 43: s = "\"char\" expected"; break;
case 44: s = "??? expected"; break;
case 45: s = "invalid AddOp"; break;
case 46: s = "invalid RelOp"; break;
case 47: s = "invalid Factor"; break;
case 48: s = "invalid Factor"; break;
case 49: s = "invalid MulOp"; break;
case 50: s = "invalid Stat"; break;
case 51: s = "invalid Stat"; break;
case 52: s = "invalid Stat"; break;
case 53: s = "invalid Stat"; break;
case 54: s = "invalid Stat"; break;
case 55: s = "invalid Type"; break;
default: s = "error " + n; break;
}
errorStream.WriteLine(errMsgFormat, line, col, s);
count++;
}
public virtual void SemErr (int line, int col, string s) {
errorStream.WriteLine(errMsgFormat, line, col, s);
count++;
}
public virtual void SemErr (string s) {
errorStream.WriteLine(s);
count++;
}
public virtual void Warning (int line, int col, string s) {
errorStream.WriteLine(errMsgFormat, line, col, s);
}
public virtual void Warning(string s) {
errorStream.WriteLine(s);
}
} // Errors
public class FatalError: Exception {
public FatalError(string m): base(m) {}
}
}