es-toolkit
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A state-of-the-art, high-performance JavaScript utility library with a small bundle size and strong type annotations.
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JavaScript
const require_toString = require("../util/toString.js");
const require_attempt = require("../function/attempt.js");
const require_defaults = require("../object/defaults.js");
const require_escape = require("./escape.js");
//#region src/compat/string/template.ts
const esTemplateRegExp = /\$\{([^\\}]*(?:\\.[^\\}]*)*)\}/g;
const unEscapedRegExp = /['\n\r\u2028\u2029\\]/g;
const noMatchExp = /($^)/;
const escapeMap = new Map([
["\\", "\\"],
["'", "'"],
["\n", "n"],
["\r", "r"],
["\u2028", "u2028"],
["\u2029", "u2029"]
]);
function escapeString(match) {
return `\\${escapeMap.get(match)}`;
}
const defaultInterpolateRegExp = /<%=([\s\S]+?)%>/g;
const templateSettings = {
escape: /<%-([\s\S]+?)%>/g,
evaluate: /<%([\s\S]+?)%>/g,
interpolate: defaultInterpolateRegExp,
variable: "",
imports: { _: {
escape: require_escape.escape,
template
} }
};
/**
* Compiles a template string into a function that can interpolate data properties.
*
* This function allows you to create a template with custom delimiters for escaping,
* evaluating, and interpolating values. It can also handle custom variable names and
* imported functions.
*
* @param string - The template string.
* @param [options] - The options object.
* @param [options.escape] - The regular expression for "escape" delimiter.
* @param [options.evaluate] - The regular expression for "evaluate" delimiter.
* @param [options.interpolate] - The regular expression for "interpolate" delimiter.
* @param [options.variable] - The data object variable name.
* @param [options.imports] - The object of imported functions.
* @param [options.sourceURL] - The source URL of the template.
* @param [guard] - The guard to detect if the function is called with `options`.
* @returns Returns the compiled template function.
*
* @example
* // Use the "escape" delimiter to escape data properties.
* const compiled = template('<%- value %>');
* compiled({ value: '<div>' }); // returns '<div>'
*
* @example
* // Use the "interpolate" delimiter to interpolate data properties.
* const compiled = template('<%= value %>');
* compiled({ value: 'Hello, World!' }); // returns 'Hello, World!'
*
* @example
* // Use the "evaluate" delimiter to evaluate JavaScript code.
* const compiled = template('<% if (value) { %>Yes<% } else { %>No<% } %>');
* compiled({ value: true }); // returns 'Yes'
*
* @example
* // Use the "variable" option to specify the data object variable name.
* const compiled = template('<%= data.value %>', { variable: 'data' });
* compiled({ value: 'Hello, World!' }); // returns 'Hello, World!'
*
* @example
* // Use the "imports" option to import functions.
* const compiled = template('<%= _.toUpper(value) %>', { imports: { _: { toUpper } } });
* compiled({ value: 'hello, world!' }); // returns 'HELLO, WORLD!'
*
* @example
* // Use the custom "escape" delimiter.
* const compiled = template('<@ value @>', { escape: /<@([\s\S]+?)@>/g });
* compiled({ value: '<div>' }); // returns '<div>'
*
* @example
* // Use the custom "evaluate" delimiter.
* const compiled = template('<# if (value) { #>Yes<# } else { #>No<# } #>', { evaluate: /<#([\s\S]+?)#>/g });
* compiled({ value: true }); // returns 'Yes'
*
* @example
* // Use the custom "interpolate" delimiter.
* const compiled = template('<$ value $>', { interpolate: /<\$([\s\S]+?)\$>/g });
* compiled({ value: 'Hello, World!' }); // returns 'Hello, World!'
*
* @example
* // Use the "sourceURL" option to specify the source URL of the template.
* const compiled = template('hello <%= user %>!', { sourceURL: 'template.js' });
*/
function template(string, options, guard) {
string = require_toString.toString(string);
if (guard) options = templateSettings;
options = require_defaults.defaults({ ...options }, templateSettings);
const delimitersRegExp = new RegExp([
options.escape?.source ?? noMatchExp.source,
options.interpolate?.source ?? noMatchExp.source,
options.interpolate === defaultInterpolateRegExp ? esTemplateRegExp.source : noMatchExp.source,
options.evaluate?.source ?? noMatchExp.source,
"$"
].join("|"), "g");
let lastIndex = 0;
let isEvaluated = false;
let source = `__p += ''`;
for (const match of string.matchAll(delimitersRegExp)) {
const [fullMatch, escapeValue, interpolateValue, esTemplateValue, evaluateValue] = match;
const { index } = match;
source += ` + '${string.slice(lastIndex, index).replace(unEscapedRegExp, escapeString)}'`;
if (escapeValue) source += ` + _.escape(${escapeValue})`;
if (interpolateValue) source += ` + ((${interpolateValue}) == null ? '' : ${interpolateValue})`;
else if (esTemplateValue) source += ` + ((${esTemplateValue}) == null ? '' : ${esTemplateValue})`;
if (evaluateValue) {
source += `;\n${evaluateValue};\n __p += ''`;
isEvaluated = true;
}
lastIndex = index + fullMatch.length;
}
const imports = require_defaults.defaults({ ...options.imports }, templateSettings.imports);
const importsKeys = Object.keys(imports);
const importValues = Object.values(imports);
const sourceURL = `//# sourceURL=${options.sourceURL ? String(options.sourceURL).replace(/[\r\n]/g, " ") : `es-toolkit.templateSource[${Date.now()}]`}\n`;
const compiledFunction = `function(${options.variable || "obj"}) {
let __p = '';
${options.variable ? "" : "if (obj == null) { obj = {}; }"}
${isEvaluated ? `function print() { __p += Array.prototype.join.call(arguments, ''); }` : ""}
${options.variable ? source : `with(obj) {\n${source}\n}`}
return __p;
}`;
const result = require_attempt.attempt(() => new Function(...importsKeys, `${sourceURL}return ${compiledFunction}`)(...importValues));
result.source = compiledFunction;
if (result instanceof Error) throw result;
return result;
}
//#endregion
exports.template = template;
exports.templateSettings = templateSettings;