100 lines
3.8 KiB
JavaScript
100 lines
3.8 KiB
JavaScript
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"use strict";
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module.exports = codegen;
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/**
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* Begins generating a function.
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* @memberof util
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* @param {string[]} functionParams Function parameter names
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* @param {string} [functionName] Function name if not anonymous
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* @returns {Codegen} Appender that appends code to the function's body
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*/
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function codegen(functionParams, functionName) {
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/* istanbul ignore if */
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if (typeof functionParams === "string") {
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functionName = functionParams;
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functionParams = undefined;
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}
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var body = [];
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/**
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* Appends code to the function's body or finishes generation.
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* @typedef Codegen
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* @type {function}
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* @param {string|Object.<string,*>} [formatStringOrScope] Format string or, to finish the function, an object of additional scope variables, if any
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* @param {...*} [formatParams] Format parameters
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* @returns {Codegen|Function} Itself or the generated function if finished
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* @throws {Error} If format parameter counts do not match
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*/
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function Codegen(formatStringOrScope) {
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// note that explicit array handling below makes this ~50% faster
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// finish the function
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if (typeof formatStringOrScope !== "string") {
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var source = toString();
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if (codegen.verbose)
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console.log("codegen: " + source); // eslint-disable-line no-console
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source = "return " + source;
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if (formatStringOrScope) {
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var scopeKeys = Object.keys(formatStringOrScope),
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scopeParams = new Array(scopeKeys.length + 1),
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scopeValues = new Array(scopeKeys.length),
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scopeOffset = 0;
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while (scopeOffset < scopeKeys.length) {
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scopeParams[scopeOffset] = scopeKeys[scopeOffset];
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scopeValues[scopeOffset] = formatStringOrScope[scopeKeys[scopeOffset++]];
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}
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scopeParams[scopeOffset] = source;
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return Function.apply(null, scopeParams).apply(null, scopeValues); // eslint-disable-line no-new-func
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}
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return Function(source)(); // eslint-disable-line no-new-func
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}
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// otherwise append to body
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var formatParams = new Array(arguments.length - 1),
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formatOffset = 0;
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while (formatOffset < formatParams.length)
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formatParams[formatOffset] = arguments[++formatOffset];
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formatOffset = 0;
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formatStringOrScope = formatStringOrScope.replace(/%([%dfijs])/g, function replace($0, $1) {
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var value = formatParams[formatOffset++];
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switch ($1) {
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case "d": case "f": return String(Number(value));
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case "i": return String(Math.floor(value));
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case "j": return JSON.stringify(value);
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case "s": return String(value);
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}
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return "%";
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});
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if (formatOffset !== formatParams.length)
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throw Error("parameter count mismatch");
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body.push(formatStringOrScope);
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return Codegen;
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}
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function toString(functionNameOverride) {
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return "function " + (functionNameOverride || functionName || "") + "(" + (functionParams && functionParams.join(",") || "") + "){\n " + body.join("\n ") + "\n}";
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}
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Codegen.toString = toString;
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return Codegen;
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}
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/**
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* Begins generating a function.
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* @memberof util
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* @function codegen
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* @param {string} [functionName] Function name if not anonymous
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* @returns {Codegen} Appender that appends code to the function's body
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* @variation 2
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*/
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/**
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* When set to `true`, codegen will log generated code to console. Useful for debugging.
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* @name util.codegen.verbose
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* @type {boolean}
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*/
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codegen.verbose = false;
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