Move SQL 2019 extension's notebook code into Azure Data Studio (#4090)

extensions/notebook/src/intellisense/text.ts

@@ -0,0 +1,72 @@
+// Copyright (c) Jupyter Development Team.
+// Distributed under the terms of the Modified BSD License.
+
+// This code is originally from @jupyterlab/packages/coreutils/src/text.ts
+// Note: this code doesn't seem to do anything in the sqlops environment since the
+// surr
+
+// javascript stores text as utf16 and string indices use "code units",
+// which stores high-codepoint characters as "surrogate pairs",
+// which occupy two indices in the javascript string.
+// We need to translate cursor_pos in the Jupyter protocol (in characters)
+// to js offset (with surrogate pairs taking two spots).
+
+const HAS_SURROGATES: boolean = '𝐚'.length > 1;
+
+/**
+ * Convert a javascript string index into a unicode character offset
+ *
+ * @param jsIdx - The javascript string index (counting surrogate pairs)
+ *
+ * @param text - The text in which the offset is calculated
+ *
+ * @returns The unicode character offset
+ */
+export function jsIndexToCharIndex(jsIdx: number, text: string): number {
+	if (!HAS_SURROGATES) {
+		// not using surrogates, nothing to do
+		return jsIdx;
+	}
+	let charIdx = jsIdx;
+	for (let i = 0; i + 1 < text.length && i < jsIdx; i++) {
+		let charCode = text.charCodeAt(i);
+		// check for surrogate pair
+		if (charCode >= 0xd800 && charCode <= 0xdbff) {
+			let nextCharCode = text.charCodeAt(i + 1);
+			if (nextCharCode >= 0xdc00 && nextCharCode <= 0xdfff) {
+				charIdx--;
+				i++;
+			}
+		}
+	}
+	return charIdx;
+}
+
+/**
+ * Get the diff between pure character count and JS-based count with 2 chars per surrogate pair.
+ *
+ * @param charIdx - The index in unicode characters
+ *
+ * @param text - The text in which the offset is calculated
+ *
+ * @returns The js-native index
+ */
+export function charCountToJsCountDiff(text: string): number {
+	let diff = 0;
+	if (!HAS_SURROGATES) {
+		// not using surrogates, nothing to do
+		return diff;
+	}
+	for (let i = 0; i + 1 < text.length; i++) {
+		let charCode = text.charCodeAt(i);
+		// check for surrogate pair
+		if (charCode >= 0xd800 && charCode <= 0xdbff) {
+			let nextCharCode = text.charCodeAt(i + 1);
+			if (nextCharCode >= 0xdc00 && nextCharCode <= 0xdfff) {
+				diff++;
+				i++;
+			}
+		}
+	}
+	return diff;
+}