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path: refactor for performance and consistency
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Improve performance by:
+ Not leaking the `arguments` object!
+ Getting the last character of a string by index, instead of
  with `.substr()` or `.slice()`

Improve code consistency by:
+ Using `[]` instead of `.charAt()` where possible
+ Using a function declaration instead of a var declaration
+ Using `.slice()` with clearer arguments
+ Checking if `dir` is truthy in `win32.format`
  (added tests for this)

Improve both by:
+ Making the reusable `trimArray()` function
+ Standardizing getting certain path statistics with
  the new `win32StatPath()` function

PR-URL: nodejs#1778
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
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@nwoltman @mscdex
nwoltman authored and mscdex committed Jul 9, 2015
1 parent d6395a9 commit 3b2da61
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Showing 2 changed files with 91 additions and 74 deletions.
139 changes: 69 additions & 70 deletions lib/path.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,29 @@ function normalizeArray(parts, allowAboveRoot) {
return res;
}

// Returns an array with empty elements removed from either end of the input
// array or the original array if no elements need to be removed
function trimArray(arr) {
var lastIndex = arr.length - 1;
var start = 0;
for (; start <= lastIndex; start++) {
if (arr[start])
break;
}

var end = lastIndex;
for (; end >= 0; end--) {
if (arr[end])
break;
}

if (start === 0 && end === lastIndex)
return arr;
if (start > end)
return [];
return arr.slice(start, end + 1);
}

// Regex to split a windows path into three parts: [*, device, slash,
// tail] windows-only
const splitDeviceRe =
Expand All @@ -62,9 +85,21 @@ function win32SplitPath(filename) {
return [device, dir, basename, ext];
}

var normalizeUNCRoot = function(device) {
function win32StatPath(path) {
var result = splitDeviceRe.exec(path),
device = result[1] || '',
isUnc = !!device && device[1] !== ':';
return {
device,
isUnc,
isAbsolute: isUnc || !!result[2], // UNC paths are always absolute
tail: result[3]
};
}

function normalizeUNCRoot(device) {
return '\\\\' + device.replace(/^[\\\/]+/, '').replace(/[\\\/]+/g, '\\');
};
}

// path.resolve([from ...], to)
win32.resolve = function() {
Expand Down Expand Up @@ -99,11 +134,11 @@ win32.resolve = function() {
continue;
}

var result = splitDeviceRe.exec(path),
device = result[1] || '',
isUnc = device && device.charAt(1) !== ':',
isAbsolute = win32.isAbsolute(path),
tail = result[3];
var result = win32StatPath(path),
device = result.device,
isUnc = result.isUnc,
isAbsolute = result.isAbsolute,
tail = result.tail;

if (device &&
resolvedDevice &&
Expand Down Expand Up @@ -147,11 +182,11 @@ win32.resolve = function() {
win32.normalize = function(path) {
assertPath(path);

var result = splitDeviceRe.exec(path),
device = result[1] || '',
isUnc = device && device.charAt(1) !== ':',
isAbsolute = win32.isAbsolute(path),
tail = result[3],
var result = win32StatPath(path),
device = result.device,
isUnc = result.isUnc,
isAbsolute = result.isAbsolute,
tail = result.tail,
trailingSlash = /[\\\/]$/.test(tail);

// Normalize the tail path
Expand All @@ -176,23 +211,19 @@ win32.normalize = function(path) {

win32.isAbsolute = function(path) {
assertPath(path);

var result = splitDeviceRe.exec(path),
device = result[1] || '',
isUnc = !!device && device.charAt(1) !== ':';
// UNC paths are always absolute
return !!result[2] || isUnc;
return win32StatPath(path).isAbsolute;
};

win32.join = function() {
function f(p) {
if (typeof p !== 'string') {
throw new TypeError('Arguments to path.join must be strings');
var paths = [];
for (var i = 0; i < arguments.length; i++) {
var arg = arguments[i];
assertPath(arg);
if (arg) {
paths.push(arg);
}
return p;
}

var paths = Array.prototype.filter.call(arguments, f);
var joined = paths.join('\\');

// Make sure that the joined path doesn't start with two slashes, because
Expand Down Expand Up @@ -232,25 +263,10 @@ win32.relative = function(from, to) {
var lowerFrom = from.toLowerCase();
var lowerTo = to.toLowerCase();

function trim(arr) {
var start = 0;
for (; start < arr.length; start++) {
if (arr[start] !== '') break;
}

var end = arr.length - 1;
for (; end >= 0; end--) {
if (arr[end] !== '') break;
}

if (start > end) return [];
return arr.slice(start, end + 1);
}
var toParts = trimArray(to.split('\\'));

var toParts = trim(to.split('\\'));

var lowerFromParts = trim(lowerFrom.split('\\'));
var lowerToParts = trim(lowerTo.split('\\'));
var lowerFromParts = trimArray(lowerFrom.split('\\'));
var lowerToParts = trimArray(lowerTo.split('\\'));

var length = Math.min(lowerFromParts.length, lowerToParts.length);
var samePartsLength = length;
Expand Down Expand Up @@ -356,15 +372,13 @@ win32.format = function(pathObject) {

var dir = pathObject.dir;
var base = pathObject.base || '';
if (dir.slice(dir.length - 1, dir.length) === win32.sep) {
return dir + base;
if (!dir) {
return base;
}

if (dir) {
return dir + win32.sep + base;
if (dir[dir.length - 1] === win32.sep) {
return dir + base;
}

return base;
return dir + win32.sep + base;
};


Expand All @@ -377,7 +391,7 @@ win32.parse = function(pathString) {
}
return {
root: allParts[0],
dir: allParts[0] + allParts[1].slice(0, allParts[1].length - 1),
dir: allParts[0] + allParts[1].slice(0, -1),
base: allParts[2],
ext: allParts[3],
name: allParts[2].slice(0, allParts[2].length - allParts[3].length)
Expand Down Expand Up @@ -418,7 +432,7 @@ posix.resolve = function() {
}

resolvedPath = path + '/' + resolvedPath;
resolvedAbsolute = path.charAt(0) === '/';
resolvedAbsolute = path[0] === '/';
}

// At this point the path should be resolved to a full absolute path, but
Expand All @@ -437,7 +451,7 @@ posix.normalize = function(path) {
assertPath(path);

var isAbsolute = posix.isAbsolute(path),
trailingSlash = path.substr(-1) === '/';
trailingSlash = path && path[path.length - 1] === '/';

// Normalize the path
path = normalizeArray(path.split('/'), !isAbsolute).join('/');
Expand All @@ -455,7 +469,7 @@ posix.normalize = function(path) {
// posix version
posix.isAbsolute = function(path) {
assertPath(path);
return path.charAt(0) === '/';
return !!path && path[0] === '/';
};

// posix version
Expand Down Expand Up @@ -487,23 +501,8 @@ posix.relative = function(from, to) {
from = posix.resolve(from).substr(1);
to = posix.resolve(to).substr(1);

function trim(arr) {
var start = 0;
for (; start < arr.length; start++) {
if (arr[start] !== '') break;
}

var end = arr.length - 1;
for (; end >= 0; end--) {
if (arr[end] !== '') break;
}

if (start > end) return [];
return arr.slice(start, end + 1);
}

var fromParts = trim(from.split('/'));
var toParts = trim(to.split('/'));
var fromParts = trimArray(from.split('/'));
var toParts = trimArray(to.split('/'));

var length = Math.min(fromParts.length, toParts.length);
var samePartsLength = length;
Expand Down Expand Up @@ -602,7 +601,7 @@ posix.parse = function(pathString) {

return {
root: allParts[0],
dir: allParts[0] + allParts[1].slice(0, allParts[1].length - 1),
dir: allParts[0] + allParts[1].slice(0, -1),
base: allParts[2],
ext: allParts[3],
name: allParts[2].slice(0, allParts[2].length - allParts[3].length)
Expand Down
26 changes: 22 additions & 4 deletions test/parallel/test-path-parse-format.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,12 @@ var winPaths = [
'\\\\server two\\shared folder\\file path.zip',
'\\\\teela\\admin$\\system32',
'\\\\?\\UNC\\server\\share'
];

var winSpecialCaseFormatTests = [
[{dir: 'some\\dir'}, 'some\\dir\\'],
[{base: 'index.html'}, 'index.html'],
[{}, '']
];

var unixPaths = [
Expand All @@ -30,6 +35,12 @@ var unixPaths = [
'C:\\foo'
];

var unixSpecialCaseFormatTests = [
[{dir: 'some/dir'}, 'some/dir/'],
[{base: 'index.html'}, 'index.html'],
[{}, '']
];

var errors = [
{method: 'parse', input: [null],
message: /Path must be a string. Received null/},
Expand Down Expand Up @@ -57,10 +68,12 @@ var errors = [
message: /'pathObject.root' must be a string or undefined, not number/},
];

check(path.win32, winPaths);
check(path.posix, unixPaths);
checkParseFormat(path.win32, winPaths);
checkParseFormat(path.posix, unixPaths);
checkErrors(path.win32);
checkErrors(path.posix);
checkFormat(path.win32, winSpecialCaseFormatTests);
checkFormat(path.posix, unixSpecialCaseFormatTests);

function checkErrors(path) {
errors.forEach(function(errorCase) {
Expand All @@ -79,8 +92,7 @@ function checkErrors(path) {
});
}


function check(path, paths) {
function checkParseFormat(path, paths) {
paths.forEach(function(element, index, array) {
var output = path.parse(element);
assert.strictEqual(path.format(output), element);
Expand All @@ -89,3 +101,9 @@ function check(path, paths) {
assert.strictEqual(output.ext, path.extname(element));
});
}

function checkFormat(path, testCases) {
testCases.forEach(function(testCase) {
assert.strictEqual(path.format(testCase[0]), testCase[1]);
});
}

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