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lexer.js
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lexer.js
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// Javascript lexer for CR-Framework
class Token {
static get tkAdd() { return 1; }
static get tkSub() { return 2; }
static get tkMul() { return 3; }
static get tkLPar() { return 11; }
static get tkRPar() { return 12; }
static get tkLBra() { return 13; }
static get tkRBra() { return 14; }
static get tkSemicolon() { return 15; }
static get tkComma () { return 16; }
static get tkAssign () { return 17; }
static get tkLSqr () { return 18; }
static get tkRSqr () { return 19; }
static get tkVar() { return 21; }
static get tkOutput() { return 22; }
static get tkUtil () { return 23; }
static get tkNumber () { return 26; }
static get tkVariable() { return 27; }
static get tkEof () { return 31; }
static get tkError() { return 32; }
static getTokenName( tk ) {
switch(tk) {
case Token.tkAdd : return "+";
case Token.tkSub : return "-";
case Token.tkMul : return "*";
case Token.tkLPar: return "(";
case Token.tkRPar: return ")";
case Token.tkLBra: return "{";
case Token.tkRBra: return "}";
case Token.tkLSqr: return "[";
case Token.tkRSqr: return "]";
case Token.tkSemicolon: return ";";
case Token.tkComma : return ",";
case Token.tkAssign : return "=";
case Token.tkVar : return "var";
case Token.tkOutput : return "output";
case Token.tkUtil : return "util";
case Token.tkNumber : return "<number>";
case Token.tkVariable : return "<variable>";
case Token.tkEof : return "<eof>";
case Token.tkError : return "<error>";
default: return null;
}
}
};
class Lexeme {
constructor() {
this.token = Token.tkError;
this.text = "";
this.number= 0;
this.length= 0;
}
getTokenName() { return Token.getTokenName(this.token); }
};
class Tokenizer {
constructor( src ) {
this.pos = 0;
this.src = src;
this.lexeme = new Lexeme();
this.posCount= 1;
this.posLine = 1;
}
get lexemePos() {
return this.pos - this.lexeme.length;
}
_yield( tk , len , offset ) {
this.lexeme.token = tk;
this.lexeme.length= len;
this.pos += offset;
this.posCount += offset;
return this.lexeme;
}
_lexComment() {
let idx = this.src.indexOf("\n",this.pos);
if( idx == -1 ) {
this.posCount += (idx - this.pos);
this.pos = this.src.length;
} else {
this.pos = idx + 1;
this.posCount = 1;
this.posLine++;
}
}
_isDigit(c) {
return c >= "0" && c <= "9";
}
_isAlpha(c) {
return (c >= "a" && c <= "z") || (c >= "A" && c <= "Z");
}
_isRestIdChar(pos) {
if(pos < this.src.length) {
let c = this.src.charAt(pos);
if(this._isDigit(c) || this._isAlpha(c) || c == "_")
return true;
}
return false;
}
_lexNumber(lh) {
let start = this.pos;
this.pos++;
// find the last digit
do {
let c = this.src.charAt(this.pos);
if(!this._isDigit(c)) break;
++this.pos;
} while(true);
let diff = (this.pos - start);
this.lexeme.number = parseInt(this.src.substr(start,diff));
this.lexeme.token = Token.tkNumber;
this.lexeme.length = diff;
this.posCount += diff;
return this.lexeme;
}
_lexVar(c) {
if(c == "v" && (this.pos + 2 < this.src.length) &&
this.src.charAt(this.pos+1) == "a" &&
this.src.charAt(this.pos+2) == "r" &&
!this._isRestIdChar(this.pos+3)) {
return this._yield(Token.tkVar,3,3);
} else if(c == "o" && (this.pos + 5 < this.src.length) &&
this.src.charAt(this.pos+1) == "u" &&
this.src.charAt(this.pos+2) == "t" &&
this.src.charAt(this.pos+3) == "p" &&
this.src.charAt(this.pos+4) == "u" &&
this.src.charAt(this.pos+5) == "t" &&
!this._isRestIdChar(this.pos+6)) {
return this._yield(Token.tkOutput,6,6);
} else if(c == "u" && (this.pos + 4 < this.src.length) &&
this.src.charAt(this.pos+1) == "n" &&
this.src.charAt(this.pos+2) == "t" &&
this.src.charAt(this.pos+3) == "i" &&
this.src.charAt(this.pos+4) == "l" &&
!this._isRestIdChar(this.pos+5)) {
return this._yield(Token.tkUntil,5,5);
} else if(this._isAlpha(c) || c == "_") {
let start = this.pos; ++this.pos;
while(this._isRestIdChar(this.pos))
++this.pos;
this.lexeme.text = this.src.substr(start,(this.pos-start));
this.lexeme.token = Token.tkVariable;
this.lexeme.length = this.pos - start;
this.posCount += this.pos - start;
return this.lexeme;
} else {
this.lexeme.text = "unrecognized token";
return this._yield(Token.tkError,0,0);
}
}
// peek the next token from stream
next() {
while(this.pos < this.src.length) {
let c = this.src.charAt(this.pos);
switch(c) {
case " ": case "\r": case "\b": case "\t":
++this.pos;
++this.posCount;
break;
case "\n":
++this.pos;
++this.posLine;
this.posCount = 1;
break;
case "#":
this._lexComment(); break;
case "=": return this._yield(Token.tkAssign,1,1);
case "+": return this._yield(Token.tkAdd,1,1);
case "-": return this._yield(Token.tkSub,1,1);
case "*": return this._yield(Token.tkMul,1,1);
case "(": return this._yield(Token.tkLPar,1,1);
case ")": return this._yield(Token.tkRPar,1,1);
case "{": return this._yield(Token.tkLBra,1,1);
case "}": return this._yield(Token.tkRBra,1,1);
case "[": return this._yield(Token.tkLSqr,1,1);
case "]": return this._yield(Token.tkRSqr,1,1);
case ";": return this._yield(Token.tkSemicolon,1,1);
case ",": return this._yield(Token.tkComma,1,1);
case "0": case "1": case "2": case "3": case "4":
case "5": case "6": case "7": case "8": case "9":
return this._lexNumber(c);
default:
return this._lexVar(c);
}
}
return this._yield(Token.tkEof,0,0);
}
};
module.exports = {
"Token" : Token ,
"Lexeme": Lexeme,
"Tokenizer": Tokenizer
};