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get-expression.js
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67 lines (54 loc) · 1.69 KB
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
// @flow
import type { Position } from "../../types";
type Token = {
startColumn: number,
endColumn: number,
type: string
};
export function tokenAtTextPosition(
cm: any,
{ line, column }: Position
): Token | null {
if (line < 0 || line >= cm.lineCount()) {
return null;
}
const token = cm.getTokenAt({ line: line - 1, ch: column });
if (!token) {
return null;
}
return { startColumn: token.start, endColumn: token.end, type: token.type };
}
// The strategy of querying codeMirror tokens was borrowed
// from Chrome's inital implementation in JavaScriptSourceFrame.js#L414
export function getExpressionFromCoords(cm: any, coord: Position) {
const token = tokenAtTextPosition(cm, coord);
if (!token) {
return null;
}
let startHighlight = token.startColumn;
const endHighlight = token.endColumn;
const lineNumber = coord.line;
const line = cm.doc.getLine(coord.line - 1);
while (startHighlight > 1 && line.charAt(startHighlight - 1) === ".") {
const tokenBefore = tokenAtTextPosition(cm, {
line: coord.line,
column: startHighlight - 2
});
if (!tokenBefore || !tokenBefore.type) {
return null;
}
startHighlight = tokenBefore.startColumn;
}
const expression = line.substring(startHighlight, endHighlight) || "";
if (!expression) {
return null;
}
const location = {
start: { line: lineNumber, column: startHighlight },
end: { line: lineNumber, column: endHighlight }
};
return { expression, location };
}