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lib/jazz/compiler.js
Maintainability
61.75
Lines of code
381
Difficulty
54.65
Estimated Errors
3.39
Function weight
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"use strict"; import events from "events"; import * as ast from "./ast.js"; /** * Compile-time error raised when AST nodes cannot be compiled. */ class CompileError extends Error { /** * Create a compile error. * * @param {string} filename: template filename * @param {number|string} row: source row number * @param {number|string} col: source column number * @param {string} message: compile error details */ constructor(filename, row, col, message) { super(message); this.name = "CompileError"; this.filename = filename; this.row = row || "?"; this.col = col || "?"; } /** * Format this compile error into a readable location-prefixed string. * * @returns {string} formatted error string */ toString() { return `${this.filename}:${this.row.toString()}:${this.col.toString()}: ${this.message.toString()}`; } } /** * Executable program generated from a Jazz template AST. */ class Program { /** * Create a program wrapper. * * @param {Function} fn: generated executable function * @param {Array<string>} globals: global variable names in call order */ constructor(fn, globals) { this.fn = fn; this.globals = globals; } // Kept for backward compatibility. /** * Execute the program against a namespace and callback. * * @param {Object} namespace: values referenced by template globals * @param {Function} cb: standard cb(result) callback * @returns {*} return value from generated function */ eval(namespace, cb) { return this.process(namespace, cb); } /** * Execute the program against a namespace and callback. * * @param {Object} namespace: values referenced by template globals * @param {Function} cb: standard cb(result) callback * @returns {*} return value from generated function */ process(namespace, cb) { const args = [cb].concat(this._namespaceToArgs(namespace)); return this.fn.apply(this.fn, args); } /** * Convert namespace values into argument list matching globals order. * * @param {Object} namespace: values keyed by global variable names * @returns {Array<*>} argument values in globals order */ _namespaceToArgs(namespace) { const args = []; for (let i = 0; i < this.globals.length; i += 1) { args.push(namespace[this.globals[i]]); } return args; } } /** * JavaScript compiler that converts Jazz AST nodes into executable code. */ class CompilerJS { /** * Create a JavaScript compiler instance. */ constructor() { this.debug = false; this.nextVar = 0; } _prologue(globals) { let code = ""; code += "(function() {\n"; code += "var __jazz_cb = arguments[0];\n"; code += "var __jazz_emitter = new events.EventEmitter();\n"; code += "var __jazz_expected = 0;\n"; code += "var __jazz_seen = 0;\n"; code += "var __jazz_output = [];\n"; code += "var __jazz_ready = false;\n"; code += "function __jazz_check_complete() {\n"; code += " if (__jazz_ready && __jazz_expected == __jazz_seen) {\n"; code += " __jazz_cb(__jazz_output.join(''));\n"; code += " }\n"; code += "}\n"; code += "__jazz_emitter.addListener('data', function(pos, chunk) {\n"; code += " __jazz_output[pos] = chunk;\n"; code += " __jazz_seen++;\n"; code += " __jazz_check_complete();\n"; code += "});\n"; for (let i = 0; i < globals.length; i += 1) { const argIndex = i + 1; code += `var ${globals[i]} = arguments[${argIndex}];\n`; } return code; } _epilogue() { let code = ""; code += "__jazz_ready = true;\n"; code += "__jazz_check_complete();\n"; code += "})"; return code; } /** * Compile the AST root node into an executable program. * * @param {ast.AST} astRoot: parsed Jazz AST * @returns {Program} executable program instance */ compile(astRoot) { let code = this._prologue(astRoot.globals); code += this._compileSuite(astRoot.root); code += this._epilogue(); return new Program(eval(code), astRoot.globals); } _newVar() { const name = `__jazz_var${this.nextVar}`; this.nextVar += 1; return name; } _compileSuite(suite) { let code = "{\n"; for (let i = 0; i < suite.body.length; i += 1) { code += this._compileStatement(suite.body[i]); } code += "}\n"; return code; } _compileStatement(stmt) { let code = ""; if (stmt.constructor === ast.IfStmt) { code += this._compileIfStmt(stmt); } else if (stmt.constructor === ast.ForEach) { code += this._compileForEach(stmt); } else if (stmt.constructor === ast.Echo) { code += this._compileEcho(stmt); } else if (stmt.constructor === ast.Call) { code += this._compileCall(stmt); } else if (stmt.constructor === ast.Suite) { code += this._compileSuite(stmt); } else if (stmt.constructor === ast.GetArr) { code += this._compileEcho(stmt); } else { throw new CompileError( "!FIXME!", stmt.row, stmt.col, `unknown statement type: ${stmt.type}`, ); } return code; } _compileEcho(stmt) { let code = ""; const slotVar = this._newVar(); code += `var ${slotVar} = __jazz_expected++;\n`; code += `__jazz_emitter.emit('data', ${slotVar}, ${this._compileExpr(stmt.value)});\n`; return code; } _compileCall(stmt) { let code = ""; const slotVar = this._newVar(); code += `var ${slotVar} = __jazz_expected++;\n`; code += `(${this._compileExpr(stmt.expr)})(`; for (let i = 0; i < stmt.args.length; i += 1) { code += this._compileExpr(stmt.args[i]); code += ", "; } code += `function(data) { __jazz_emitter.emit('data', ${slotVar}, data); });\n`; return code; } _compileIfStmt(stmt) { let code = "if ("; code += this._compileExpr(stmt.expr); code += ") "; code += this._compileSuite(stmt.suite); if (stmt.orelse) { code += ` else ${this._compileStatement(stmt.orelse)}`; } return code; } _compileForEach(stmt) { const exprVar = this._newVar(); const indexVar = this._newVar(); const lengthVar = this._newVar(); const countVar = this._newVar(); let code = `var ${exprVar} = ${this._compileExpr(stmt.expr)};\n`; code += `if (${exprVar} instanceof Array) {\n`; code += `var ${lengthVar} = ${exprVar} ? ${exprVar}.length : 0;\n`; code += `for (var ${indexVar} = 0, ${countVar} = 1; ${indexVar} < ${lengthVar}; ${indexVar}++, ${countVar}++) `; code += "(function() {\n"; code += ` var __index = ${indexVar};\n`; code += ` var __count = ${countVar};\n`; code += ` var ${stmt.ident.name} = ${exprVar}[${indexVar}];\n`; code += ` ${this._compileSuite(stmt.suite)}`; code += "})();\n"; code += "}\n"; code += "else {\n"; code += `var ${countVar} = 1;\n`; code += `for (var ${indexVar} in ${exprVar}) `; code += "(function() {\n"; code += ` if (${exprVar}.hasOwnProperty(${indexVar})) {\n`; code += ` var __index = ${indexVar};\n`; code += ` var __count = ${countVar};\n`; code += ` var ${stmt.ident.name} = {'key': __index, 'value': ${exprVar}[__index]};\n`; code += ` ${this._compileSuite(stmt.suite)}\n`; code += ` ${countVar}++;\n`; code += " }\n"; code += "})();\n"; code += "}\n"; return code; } _compileHash(hash) { let code = "{"; const body = hash.body; for (let i = 0; i < body.length; i += 1) { const element = body[i]; code += this._compileExpr(element[0]); code += ":"; code += this._compileExpr(element[1]); if (i < body.length - 1) { code += ","; } } code += "}"; return code; } _compileExpr(expr) { if (expr.constructor === ast.Ident) { return expr.name; } if (expr.constructor === ast.GetAttr) { if (expr.array) { return `(${this._compileExpr(expr.expr)})[${this._compileExpr(expr.id)}]`; } return `(${this._compileExpr(expr.expr)}).${this._compileExpr(expr.id)}`; } if (expr.constructor === ast.And) { return `((${this._compileExpr(expr.left)}) && (${this._compileExpr(expr.right)}))`; } if (expr.constructor === ast.Or) { return `((${this._compileExpr(expr.left)}) || (${this._compileExpr(expr.right)}))`; } if (expr.constructor === ast.Not) { return `(!(${this._compileExpr(expr.expr)}))`; } if (expr.constructor === ast.BinOp) { return `((${this._compileExpr(expr.left)})${expr.op}(${this._compileExpr(expr.right)}))`; } if (expr.constructor === ast.Str) { return `"${expr.value .replace(/\r/g, "\\r") .replace(/\n/g, "\\n") .replace(/\t/g, "\\t") .replace(/"/g, '\\"')}"`; } if (expr.constructor === ast.Num) { return expr.value; } if (expr.constructor === ast.Bool) { return expr.value; } if (expr.constructor === ast.Empty) { const compiledExpr = this._compileExpr(expr.expr); let statement = "("; statement += `!${compiledExpr} || `; statement += `(${compiledExpr} instanceof Array && ${compiledExpr}.length == 0)`; statement += ")"; return statement; } if (expr.constructor === ast.Hash) { return this._compileHash(expr); } if (expr.constructor === ast.SyncCall) { let code = ""; const argsLength = expr.args.length; code += `(${this._compileExpr(expr.expr)})(`; for (let i = 0; i < argsLength; i += 1) { code += this._compileExpr(expr.args[i]); if (i !== argsLength - 1) { code += ", "; } } code += ")"; return code; } if (expr.constructor === ast.GetArr) { return `(${this._compileExpr(expr.expr)})[${this._compileExpr(expr.index)}]`; } throw new CompileError( "!FIXME!", expr.row, expr.col, `unknown expression type: ${JSON.stringify(expr)}`, ); } } /** * Create a default JavaScript compiler. * * @returns {CompilerJS} compiler instance */ function createCompiler() { return new CompilerJS(); } export { CompileError, Program, CompilerJS, createCompiler, events }; export default { CompileError, Program, CompilerJS, createCompiler, };