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LexicalAnalyzer.js
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LexicalAnalyzer.js
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// add your input test between ` `
const initialInput =
`
for(;;)
$
`;
let newInput = initialInput.replace(/ +/g, ' ');
// create a new object of Buffer class
let buffer = new Buffer(newInput);
// create a new object of LineTracker class
let lineTracker = new LineTracker();
// create an array for tokenTable
tokenTable = new Array();
// define and initialize the satate variable
let state = 0;
let numberValue = '';
//
let token;
/*
* isReserved Function
* check if the string is not a reserved word
*/
function isReserved(c){
switch(c){
case 'if':
return 'if';
case 'else':
return 'else';
case 'for':
return 'for';
case 'while':
return 'while';
case 'int':
return 'int';
case 'float':
return 'float';
case 'char':
return 'char';
case 'struct':
return 'struct';
case 'null':
return 'null';
case 'switch':
return 'switch';
case 'case':
return 'case';
case 'class':
return 'class';
case 'signed':
return 'signed';
case 'unsigned':
return 'unsigned';
case 'enum':
return 'enum';
case 'struct':
return 'struct';
case 'void':
return 'void';
case 'define':
return 'define';
default:
return 'id';
}
}
/*
* isCharacterALetter Function
* check if the charachter is a letter
*/
function isCharacterALetter(c) {
if(c===undefined)
return false;
return /[a-zA-Z_]/.test(c);
}
/*
* isCharacterADigit Function
* check if the charachter is a digit
*/
function isCharacterADigit(c){
return /[0-9]/.test(c);
}
function fail() {
buffer.deleteCurrentLexeme();
switch(state){
case 0: state = 3; /*Identifier*/
break;
case 3: state = 4; /*Space*/
break;
case 4: state = 5; /*Line Break*/
break;
case 5: /*Number*/
case 7:
case 8:
case 9:
case 10:
case 11: state = 15;
break;
case 15: /*Relational Oprations*/
case 22:
case 24: state = 26; /*Basic math Oprations*/
break;
case 26: state = 27;
break;
case 27: state = 28;
break;
case 28: state = 30;
break;
case 30: state = 31;
break;
case 31: state = 32; /*Symbols*/
break;
case 32: state = 33;
break;
case 33: state = 34;
break;
case 34: state = 35;
break;
case 35: state = 36;
break;
case 36: state = 37;
break;
case 37: state = 38;
break;
case 38: state = 39;
break;
case 39: state = 40;
break;
case 40: state = 41;
break;
case 41: state = 42;
break;
case 42: state = 43;
break;
case 43: state = 44;
break;
case 44: state = 46; /*End of code*/
break;
case 46: state = 47; /*Error*/
break;
}
}
function lexicalAnalyze(){
let c = '';
while(1){
switch(state){
case 0:
c = buffer.nextChar();
if(isCharacterALetter(c)){
state = 1;
}else{
fail();
}
break;
case 1:
c = buffer.nextChar();
if(!(isCharacterALetter(c) || isCharacterADigit(c))){
state = 2;
}
break;
case 2:
buffer.retract();
let lexeme = buffer.takeLexeme();
let lexemeType = isReserved(lexeme);
if(lexemeType==='id'){
token = new Token('id');
token.value = lexeme;
token.line = lineTracker.currentLine();
}else{
token = new Token(lexemeType);
token.value = lexemeType;
token.line = lineTracker.currentLine();
}
tokenTable.push(token);
state = 0;
break;
case 3:
c = buffer.nextChar();
if (c ===' '){
buffer.takeLexeme();
state = 0;
}
else
fail();
break;
case 4:
c = buffer.nextChar();
if (c == '\n'){
buffer.takeLexeme();
lineTracker.nextLine();
state = 0;
}
else
fail();
break;
case 5:
c = buffer.nextChar();
if (isCharacterADigit(c))
state = 6;
else
fail();
break;
case 6:
c = buffer.nextChar();
if(isCharacterADigit(c))
state = 6;
else if(c == ".")
state = 7
else if(c == "E")
state = 9;
else if(!(isCharacterALetter(c) || isCharacterADigit(c)))
state = 13;
else
fail();
break;
case 7:
c = buffer.nextChar();
if(isCharacterADigit(c))
state = 8;
else
fail();
break;
case 8:
c = buffer.nextChar();
if(isCharacterADigit(c))
state = 8;
else if(!(isCharacterALetter(c) || isCharacterADigit(c)))
state = 14;
else if(c == "E")
state = 9;
else
fail();
break;
case 9:
c = buffer.nextChar();
if(c == "+" || c == "-")
state = 10;
else if(isCharacterADigit(c))
state = 11;
else
fail();
break;
case 10:
c = buffer.nextChar();
if(isCharacterADigit(c))
state = 11;
else
fail();
break;
case 11:
c = buffer.nextChar();
if(isCharacterADigit(c))
state = 11;
else if(!(isCharacterALetter(c) || isCharacterADigit(c)))
state = 12;
else
fail();
break;
case 12:
buffer.retract();
numberValue = buffer.takeLexeme();
token = new Token('number');
token.value = numberValue;
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 13:
buffer.retract();
numberValue = buffer.takeLexeme();
token = new Token('number');
token.value = numberValue;
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 14:
buffer.retract();
numberValue = buffer.takeLexeme();
token = new Token('number');
token.value = numberValue;
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 15:
c = buffer.nextChar();
if(c == '<')
state = 16;
else if(c == '>')
state = 19;
else if(c == '=')
state = 22;
else if(c == '!')
state = 24;
else
fail();
break;
case 16:
c = buffer.nextChar();
if(c == '=')
state = 17;
else
state = 18;
break;
case 17:
buffer.takeLexeme();
token = new Token("<=");
token.value = "<=";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 18:
buffer.retract();
buffer.takeLexeme();
token = new Token("<");
token.value = "<";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 19:
c = buffer.nextChar();
if(c == '=')
state = 20;
else
state = 21;
break;
case 20:
buffer.takeLexeme();
token = new Token(">=");
token.value = ">=";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 21:
buffer.retract();
buffer.takeLexeme();
token = new Token(">");
token.value = ">";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 22:
c = buffer.nextChar();
if(c == '=')
state = 23;
else
fail();
break;
case 23:
buffer.takeLexeme();
token = new Token("==");
token.value = "==";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 24:
c = buffer.nextChar();
if(c == '=')
state = 25;
else
fail();
break;
case 25:
buffer.takeLexeme();
token = new Token("!=");
token.value = "!=";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
break;
case 26:
c = buffer.nextChar();
if(c == '+'){
buffer.takeLexeme();
token = new Token("+");
token.value = "+";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 27:
c = buffer.nextChar();
if(c == '-'){
buffer.takeLexeme();
token = new Token("-");
token.value = "-";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 28:
c = buffer.nextChar();
if(c == '*')
state = 29;
else
fail();
break;
case 29:
c = buffer.nextChar();
if(c == '*'){
buffer.takeLexeme();
token = new Token("**");
token.value = "**";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else{
buffer.retract();
buffer.takeLexeme();
token = new Token("*");
token.value = "*";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}
break;
case 30:
c = buffer.nextChar();
if(c == '/'){
buffer.takeLexeme();
token = new Token("/");
token.value = "/";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 31:
c = buffer.nextChar();
if(c == '='){
buffer.takeLexeme();
token = new Token("=");
token.value = "=";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 32:
c = buffer.nextChar();
if(c == '!'){
buffer.takeLexeme();
token = new Token("!");
token.value = "!";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 33:
c = buffer.nextChar();
if(c == '('){
buffer.takeLexeme();
token = new Token("(");
token.value = "(";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 34:
c = buffer.nextChar();
if(c == ')'){
buffer.takeLexeme();
token = new Token(")");
token.value = ")";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 35:
c = buffer.nextChar();
if(c == '{'){
buffer.takeLexeme();
token = new Token("{");
token.value = "{";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 36:
c = buffer.nextChar();
if(c == '}'){
buffer.takeLexeme();
token = new Token("}");
token.value = "}";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 37:
c = buffer.nextChar();
if(c == '&'){
c = buffer.nextChar();
if(c == '&'){
buffer.takeLexeme();
token = new Token("&&");
token.value = "&&";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else fail();
}else if(c == '|'){
c = buffer.nextChar();
if(c == '|'){
buffer.takeLexeme();
token = new Token("||");
token.value = "||";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else fail();
}else
fail();
break;
case 38:
c = buffer.nextChar();
if(c == '['){
buffer.takeLexeme();
token = new Token("[");
token.value = "[";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 39:
c = buffer.nextChar();
if(c == ']'){
buffer.takeLexeme();
token = new Token("]");
token.value = "]";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 40:
c = buffer.nextChar();
if(c == ';'){
buffer.takeLexeme();
token = new Token(";");
token.value = ";";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 41:
c = buffer.nextChar();
if(c == ':'){
buffer.takeLexeme();
token = new Token(":");
token.value = ":";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 42:
c = buffer.nextChar();
if(c == '\"'){
buffer.takeLexeme();
token = new Token("\"");
token.value = "\"";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 43:
c = buffer.nextChar();
if(c == '\''){
buffer.takeLexeme();
token = new Token("\'");
token.value = "\'";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else
fail();
break;
case 44:
c = buffer.nextChar();
if(c == '\\')
state = 45;
else
fail();
break;
case 45:
c = buffer.nextChar();
if('\\'){
buffer.takeLexeme();
token = new Token("\\\\");
token.value = "\\\\";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}else{
buffer.retract();
buffer.takeLexeme();
token = new Token("\\");
token.value = "\\";
token.line = lineTracker.currentLine();
tokenTable.push(token);
state = 0;
}
case 46:
if(c === '$')
return;
else
fail();
break;
case 47:
currentChar = buffer.nextChar();
buffer.takeLexeme();
state = 0;
let errorStatement = "\'" + currentChar +"\'" +" on line: "+ lineTracker.currentLine() + " matches no pattern";
console.log(errorStatement);
break;
}
}
}
// calling
lexicalAnalyze();