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import { Exception } from "./errors.ts";import { extname } from "../deps/path.ts";
/** Generic class to store and retrieve items related with extensions */export default class Extensions<Value> {  default?: Value;  entries: [string, Value][] = [];
  constructor(defaultValue?: Value) {    this.default = defaultValue;  }
  /** Assign a value to a extension */  set(extension: string, value: Value): void {    if (extension === "*") {      this.default = value;      return;    }
    // If extension is already defined, we remove it.    this.delete(extension);
    // Simple extension (.ts, .js, .json)    if (extension.match(/^\.\w+$/)) {      this.entries.push([extension, value]);      return;    }
    // Chained extension (.tmpl.js, .windi.css) goes first    if (extension.match(/^\.\w+\.\w+$/)) {      this.entries.unshift([extension, value]);      return;    }
    throw new Exception(      "Invalid extension. It must start with '.' or be '*'",      { extension },    );  }
  /** Get the value assigned to an extension */  get(extension: string): Value | undefined {    if (extension === "*") {      return this.default;    }    const entry = this.entries.find(([ext]) => ext === extension);    return entry ? entry[1] : this.default;  }
  /** Delete a extension */  delete(extension: string): void {    if (extension === "*") {      this.default = undefined;      return;    }    const index = this.entries.findIndex(([ext]) => ext === extension);    if (index !== -1) {      this.entries.splice(index, 1);    }  }
  /** Search a extension/value pair for a path */  search(path: string): [string, Value] | undefined {    for (const [extension, value] of this.entries) {      if (path.endsWith(extension)) {        return [extension, value];      }    }
    return this.default ? [extname(path), this.default] : undefined;  }
  /** Return all values */  values(): Value[] {    return this.entries.map(([, value]) => value);  }}