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IonSharedSymbolTable.ts
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IonSharedSymbolTable.ts
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/*!
* Copyright 2012 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
/**
* A shared symbol table.
* @see https://amazon-ion.github.io/ion-docs/docs/symbols.html#shared-symbol-tables
*/
export class SharedSymbolTable {
protected readonly _idsByText: Map<string, number>;
constructor(
private readonly _name: string,
private readonly _version: number,
private readonly _symbols: string[]
) {
this._idsByText = new Map<string, number>();
this._numberOfSymbols = this._symbols.length;
// Iterate through the symbol array in reverse order so if the same string appears more than
// once the smaller symbol ID is stored.
for (let m = _symbols.length - 1; m >= 0; m--) {
this._idsByText.set(_symbols[m], m);
}
}
protected _numberOfSymbols: number;
get numberOfSymbols(): number {
return this._numberOfSymbols;
}
get name(): string {
return this._name;
}
get version(): number {
return this._version;
}
getSymbolText(symbolId: number): string | undefined {
if (symbolId < 0) {
throw new Error(
`Index ${symbolId} is out of bounds for the SharedSymbolTable name=${this.name}, version=${this.version}`
);
}
if (symbolId >= this.numberOfSymbols) {
return undefined;
}
return this._symbols[symbolId];
}
getSymbolId(text: string): number | undefined {
return this._idsByText.get(text);
}
}