mirror of
https://github.com/ckaczor/azuredatastudio.git
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71 lines
2.1 KiB
TypeScript
71 lines
2.1 KiB
TypeScript
// Copyright (c) Jupyter Development Team.
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// Distributed under the terms of the Modified BSD License.
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// This code is originally from @jupyterlab/packages/coreutils/src/text.ts
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// Note: this code doesn't seem to do anything in the sqlops environment since the
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// surr
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// javascript stores text as utf16 and string indices use "code units",
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// which stores high-codepoint characters as "surrogate pairs",
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// which occupy two indices in the javascript string.
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// We need to translate cursor_pos in the Jupyter protocol (in characters)
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// to js offset (with surrogate pairs taking two spots).
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const HAS_SURROGATES: boolean = '𝐚'.length > 1;
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/**
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* Convert a javascript string index into a unicode character offset
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*
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* @param jsIdx - The javascript string index (counting surrogate pairs)
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*
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* @param text - The text in which the offset is calculated
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*
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* @returns The unicode character offset
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*/
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export function jsIndexToCharIndex(jsIdx: number, text: string): number {
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if (!HAS_SURROGATES) {
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// not using surrogates, nothing to do
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return jsIdx;
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}
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let charIdx = jsIdx;
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for (let i = 0; i + 1 < text.length && i < jsIdx; i++) {
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let charCode = text.charCodeAt(i);
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// check for surrogate pair
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if (charCode >= 0xD800 && charCode <= 0xDBFF) {
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let nextCharCode = text.charCodeAt(i + 1);
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if (nextCharCode >= 0xDC00 && nextCharCode <= 0xDFFF) {
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charIdx--;
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i++;
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}
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}
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}
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return charIdx;
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}
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/**
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* Get the diff between pure character count and JS-based count with 2 chars per surrogate pair.
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*
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* @param text - The text in which the offset is calculated
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*
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* @returns The js-native index
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*/
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export function charCountToJsCountDiff(text: string): number {
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let diff = 0;
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if (!HAS_SURROGATES) {
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// not using surrogates, nothing to do
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return diff;
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}
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for (let i = 0; i + 1 < text.length; i++) {
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let charCode = text.charCodeAt(i);
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// check for surrogate pair
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if (charCode >= 0xD800 && charCode <= 0xDBFF) {
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let nextCharCode = text.charCodeAt(i + 1);
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if (nextCharCode >= 0xDC00 && nextCharCode <= 0xDFFF) {
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diff++;
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i++;
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}
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}
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}
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return diff;
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}
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