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17 August 2013 Compilers 101 An introduction to programming languages and parsing Tuesday, September 3, 13

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17 August 2013 Compilers 101 An introduction to programming languages and parsing WARNING CONTAINS CODE 0 0 0 1 1 Tuesday, September 3, 13

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gist.io/6256943 Tuesday, September 3, 13

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Tuesday, September 3, 13

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Tuesday, September 3, 13

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green big ball Tuesday, September 3, 13

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green big ball big green ball Tuesday, September 3, 13

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Tuesday, September 3, 13

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A compiler is Tuesday, September 3, 13

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A compiler is a program that translates code Tuesday, September 3, 13

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A compiler is a program that translates code from one language to another. Tuesday, September 3, 13

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A compiler is a program that translates code from one language to another. ✤ to machine code (like FORTRAN, C, Go) Tuesday, September 3, 13

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A compiler is a program that translates code from one language to another. ✤ to machine code (like FORTRAN, C, Go) ✤ to bytecode (like Java, Python) Tuesday, September 3, 13

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A compiler is a program that translates code from one language to another. ✤ to machine code (like FORTRAN, C, Go) ✤ to bytecode (like Java, Python) ✤ to another high-level language (cfront, LESS & Sass, CoffeeScript, Traceur, emscripten) Tuesday, September 3, 13

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Tuesday, September 3, 13

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Language is a different kind of data. Tuesday, September 3, 13

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Language is a different kind of data. It’s not line-based. Tuesday, September 3, 13

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Language is a different kind of data. It’s not line-based. It’s not record-based. Tuesday, September 3, 13

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Language is a different kind of data. It’s not line-based. It’s not record-based. And you can’t fake understanding. Tuesday, September 3, 13

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Language is a different kind of data. It’s not line-based. It’s not record-based. And you can’t fake understanding. Language has structure. Tuesday, September 3, 13

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when flag clicked forever point towards mouse-pointer if move 3 * speed steps not touching mouse-pointer ? then Tuesday, September 3, 13

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when flag clicked forever point towards mouse-pointer if move 3 * speed steps not touching mouse-pointer ? then Tuesday, September 3, 13

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Inside a compiler Tuesday, September 3, 13

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Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) back end (code generation) Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) back end (code generation) Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) back end (code generation) sleep(2*x) Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) back end (code generation) sleep(2*x) pushq %rbp movq %rsp, %rbp addl %edi, %edi callq _sleep Inside a compiler Tuesday, September 3, 13

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front end (parsing, analysis) back end (code generation) sleep(2*x) call sleep * 2 x pushq %rbp movq %rsp, %rbp addl %edi, %edi callq _sleep Inside a compiler Tuesday, September 3, 13

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Inside a front end Tuesday, September 3, 13

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Inside a front end tokenizer Tuesday, September 3, 13

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Inside a front end tokenizer parser Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x ['12', '*', 'x'] Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x ['12', '*', 'x'] Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x ['12', '*', 'x'] out.number('12') Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x ['12', '*', 'x'] out.number('12') out.name('x') Tuesday, September 3, 13

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Inside a front end tokenizer parser AST builder 12*x * 12 x ['12', '*', 'x'] out.number('12') out.name('x') out.mul( , ) Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement Tuesday, September 3, 13

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Statement : Block VariableStatement EmptyStatement ExpressionStatement IfStatement IterationStatement ContinueStatement BreakStatement ReturnStatement WithStatement LabelledStatement Tuesday, September 3, 13

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PrimaryExpr : Number Name ( Expr ) MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Expr : MulExpr ( + MulExpr | - MulExpr )* Tuesday, September 3, 13

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PrimaryExpr : Number Name ( Expr ) MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Expr : MulExpr ( + MulExpr | - MulExpr )* out.number("3") Tuesday, September 3, 13

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PrimaryExpr : Number Name ( Expr ) MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Expr : MulExpr ( + MulExpr | - MulExpr )* out.number("3") out.name("pi") Tuesday, September 3, 13

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PrimaryExpr : Number Name ( Expr ) MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Expr : MulExpr ( + MulExpr | - MulExpr )* out.number("3") out.name("pi") out.mul(lhs, rhs) Tuesday, September 3, 13

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PrimaryExpr : Number Name ( Expr ) MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Expr : MulExpr ( + MulExpr | - MulExpr )* out.number("3") out.name("pi") out.mul(lhs, rhs) out.add(lhs, rhs) Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parse(code, out) { var tokens = tokenize(code); var position = 0; function peek() { return tokens[position]; } function consume(token) { assert.strictEqual(token, tokens[position]); position++; } Calculator parser - page 1 of 5 Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Calculator parser - page 2 of 5 PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseMulExpr() { var expr = parsePrimaryExpr(); var t = peek(); while (t === "*" || t === "/") { consume(t); var rhs = parsePrimaryExpr(); if (t === "*") expr = out.mul(expr, rhs); else expr = out.div(expr, rhs); t = peek(); } return expr; } Calculator parser - page 3 of 5 MulExpr : PrimaryExpr ( * PrimaryExpr | / PrimaryExpr )* Tuesday, September 3, 13

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function parseExpr() { var expr = parseMulExpr(); var t = peek(); while (t === "+" || t === "-") { consume(t); var rhs = parseMulExpr(); if (t === "+") expr = out.add(expr, rhs); else expr = out.sub(expr, rhs); t = peek(); } return expr; } Calculator parser - page 4 of 5 Expr : MulExpr ( + MulExpr | - MulExpr )* Tuesday, September 3, 13

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Calculator parser - page 5 of 5 var result = parseExpr(); if (position !== tokens.length) { throw new SyntaxError( "unexpected '" + peek() + "'"); } return result; } Tuesday, September 3, 13

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Calculator parser - page 5 of 5 var result = parseExpr(); if (position !== tokens.length) { throw new SyntaxError( "unexpected '" + peek() + "'"); } return result; } Tuesday, September 3, 13

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Calculator parser - page 5 of 5 var result = parseExpr(); if (position !== tokens.length) { throw new SyntaxError( "unexpected '" + peek() + "'"); } return result; } Tuesday, September 3, 13

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Calculator parser - page 5 of 5 var result = parseExpr(); if (position !== tokens.length) { throw new SyntaxError( "unexpected '" + peek() + "'"); } return result; } Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement PrimaryExpr : Number Name ( Expr ) Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement PrimaryExpr : Number Name ( Expr ) function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Tuesday, September 3, 13

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IfStatement : if ( Expression ) Statement else Statement if ( Expression ) Statement PrimaryExpr : Number Name ( Expr ) function parsePrimaryExpr() { var t = peek(); if (isNumber(t)) { consume(t); return out.number(t); } else if (isName(t)) { consume(t); return out.name(t); } else if (t === "(") { consume(t); var expr = parseExpr(); if (peek() !== ")") throw new SyntaxError("expected )"); consume(")"); return expr; } else { throw new SyntaxError("didn't expect '" + t + "'"); } } Tuesday, September 3, 13

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join me tomorrow for Compilers 101L Tuesday, September 3, 13