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/* -*- indent-tabs-mode: nil; js-indent-level: 2; fill-column: 80 -*- */
/* vim:set ts=2 sw=2 sts=2 et tw=80:
* 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/. */
"use strict";
const Services = require("Services");
const EXPAND_TAB = "devtools.editor.expandtab";
const TAB_SIZE = "devtools.editor.tabsize";
const DETECT_INDENT = "devtools.editor.detectindentation";
const DETECT_INDENT_MAX_LINES = 500;
/**
* Get the indentation to use in an editor, or return false if the user has
* asked for the indentation to be guessed from some text.
*
* @return {false | Object}
* Returns false if the "detect indentation" pref is set.
* an object of the form {indentUnit, indentWithTabs}.
* |indentUnit| is the number of indentation units to use
* to indent a "block".
* |indentWithTabs| is a boolean which is true if indentation
* should be done using tabs.
*/
function getIndentationFromPrefs() {
let shouldDetect = Services.prefs.getBoolPref(DETECT_INDENT);
if (shouldDetect) {
return false;
}
let indentWithTabs = !Services.prefs.getBoolPref(EXPAND_TAB);
let indentUnit = Services.prefs.getIntPref(TAB_SIZE);
return {indentUnit, indentWithTabs};
}
/**
* Given a function that can iterate over some text, compute the indentation to
* use. This consults various prefs to arrive at a decision.
*
* @param {Function} iterFunc A function of three arguments:
* (start, end, callback); where |start| and |end| describe
* the range of text lines to examine, and |callback| is a function
* to be called with the text of each line.
*
* @return {Object} an object of the form {indentUnit, indentWithTabs}.
* |indentUnit| is the number of indentation units to use
* to indent a "block".
* |indentWithTabs| is a boolean which is true if indentation
* should be done using tabs.
*/
function getIndentationFromIteration(iterFunc) {
let indentWithTabs = !Services.prefs.getBoolPref(EXPAND_TAB);
let indentUnit = Services.prefs.getIntPref(TAB_SIZE);
let shouldDetect = Services.prefs.getBoolPref(DETECT_INDENT);
if (shouldDetect) {
let indent = detectIndentation(iterFunc);
if (indent != null) {
indentWithTabs = indent.tabs;
indentUnit = indent.spaces ? indent.spaces : indentUnit;
}
}
return {indentUnit, indentWithTabs};
}
/**
* A wrapper for @see getIndentationFromIteration which computes the
* indentation of a given string.
*
* @param {String} string the input text
* @return {Object} an object of the same form as returned by
* getIndentationFromIteration
*/
function getIndentationFromString(string) {
let iteratorFn = function (start, end, callback) {
let split = string.split(/\r\n|\r|\n|\f/);
split.slice(start, end).forEach(callback);
};
return getIndentationFromIteration(iteratorFn);
}
/**
* Detect the indentation used in an editor. Returns an object
* with 'tabs' - whether this is tab-indented and 'spaces' - the
* width of one indent in spaces. Or `null` if it's inconclusive.
*/
function detectIndentation(textIteratorFn) {
// # spaces indent -> # lines with that indent
let spaces = {};
// indentation width of the last line we saw
let last = 0;
// # of lines that start with a tab
let tabs = 0;
// # of indented lines (non-zero indent)
let total = 0;
textIteratorFn(0, DETECT_INDENT_MAX_LINES, (text) => {
if (text.startsWith("\t")) {
tabs++;
total++;
return;
}
let width = 0;
while (text[width] === " ") {
width++;
}
// don't count lines that are all spaces
if (width == text.length) {
last = 0;
return;
}
if (width > 1) {
total++;
}
// see how much this line is offset from the line above it
let indent = Math.abs(width - last);
if (indent > 1 && indent <= 8) {
spaces[indent] = (spaces[indent] || 0) + 1;
}
last = width;
});
// this file is not indented at all
if (total == 0) {
return null;
}
// mark as tabs if they start more than half the lines
if (tabs >= total / 2) {
return { tabs: true };
}
// find most frequent non-zero width difference between adjacent lines
let freqIndent = null, max = 1;
for (let width in spaces) {
width = parseInt(width, 10);
let tally = spaces[width];
if (tally > max) {
max = tally;
freqIndent = width;
}
}
if (!freqIndent) {
return null;
}
return { tabs: false, spaces: freqIndent };
}
exports.EXPAND_TAB = EXPAND_TAB;
exports.TAB_SIZE = TAB_SIZE;
exports.DETECT_INDENT = DETECT_INDENT;
exports.getIndentationFromPrefs = getIndentationFromPrefs;
exports.getIndentationFromIteration = getIndentationFromIteration;
exports.getIndentationFromString = getIndentationFromString;
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