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parse.ts
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parse.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
import { CHAR_COLON, CHAR_DOT } from "../_common/constants.ts";
import type { ParsedPath } from "../_interface.ts";
import { assertPath } from "../_common/assert_path.ts";
import { isPathSeparator, isWindowsDeviceRoot } from "./_util.ts";
/**
* Return a `ParsedPath` object of the `path`.
* @param path to process
*/
export function parse(path: string): ParsedPath {
assertPath(path);
const ret: ParsedPath = { root: "", dir: "", base: "", ext: "", name: "" };
const len = path.length;
if (len === 0) return ret;
let rootEnd = 0;
let code = path.charCodeAt(0);
// Try to match a root
if (len > 1) {
if (isPathSeparator(code)) {
// Possible UNC root
rootEnd = 1;
if (isPathSeparator(path.charCodeAt(1))) {
// Matched double path separator at beginning
let j = 2;
let last = j;
// Match 1 or more non-path separators
for (; j < len; ++j) {
if (isPathSeparator(path.charCodeAt(j))) break;
}
if (j < len && j !== last) {
// Matched!
last = j;
// Match 1 or more path separators
for (; j < len; ++j) {
if (!isPathSeparator(path.charCodeAt(j))) break;
}
if (j < len && j !== last) {
// Matched!
last = j;
// Match 1 or more non-path separators
for (; j < len; ++j) {
if (isPathSeparator(path.charCodeAt(j))) break;
}
if (j === len) {
// We matched a UNC root only
rootEnd = j;
} else if (j !== last) {
// We matched a UNC root with leftovers
rootEnd = j + 1;
}
}
}
}
} else if (isWindowsDeviceRoot(code)) {
// Possible device root
if (path.charCodeAt(1) === CHAR_COLON) {
rootEnd = 2;
if (len > 2) {
if (isPathSeparator(path.charCodeAt(2))) {
if (len === 3) {
// `path` contains just a drive root, exit early to avoid
// unnecessary work
ret.root = ret.dir = path;
ret.base = "\\";
return ret;
}
rootEnd = 3;
}
} else {
// `path` contains just a relative drive root, exit early to avoid
// unnecessary work
ret.root = ret.dir = path;
return ret;
}
}
}
} else if (isPathSeparator(code)) {
// `path` contains just a path separator, exit early to avoid
// unnecessary work
ret.root = ret.dir = path;
ret.base = "\\";
return ret;
}
if (rootEnd > 0) ret.root = path.slice(0, rootEnd);
let startDot = -1;
let startPart = rootEnd;
let end = -1;
let matchedSlash = true;
let i = path.length - 1;
// Track the state of characters (if any) we see before our first dot and
// after any path separator we find
let preDotState = 0;
// Get non-dir info
for (; i >= rootEnd; --i) {
code = path.charCodeAt(i);
if (isPathSeparator(code)) {
// If we reached a path separator that was not part of a set of path
// separators at the end of the string, stop now
if (!matchedSlash) {
startPart = i + 1;
break;
}
continue;
}
if (end === -1) {
// We saw the first non-path separator, mark this as the end of our
// extension
matchedSlash = false;
end = i + 1;
}
if (code === CHAR_DOT) {
// If this is our first dot, mark it as the start of our extension
if (startDot === -1) startDot = i;
else if (preDotState !== 1) preDotState = 1;
} else if (startDot !== -1) {
// We saw a non-dot and non-path separator before our dot, so we should
// have a good chance at having a non-empty extension
preDotState = -1;
}
}
if (
startDot === -1 ||
end === -1 ||
// We saw a non-dot character immediately before the dot
preDotState === 0 ||
// The (right-most) trimmed path component is exactly '..'
(preDotState === 1 && startDot === end - 1 && startDot === startPart + 1)
) {
if (end !== -1) {
ret.base = ret.name = path.slice(startPart, end);
}
} else {
ret.name = path.slice(startPart, startDot);
ret.base = path.slice(startPart, end);
ret.ext = path.slice(startDot, end);
}
// Fallback to '\' in case there is no basename
ret.base = ret.base || "\\";
// If the directory is the root, use the entire root as the `dir` including
// the trailing slash if any (`C:\abc` -> `C:\`). Otherwise, strip out the
// trailing slash (`C:\abc\def` -> `C:\abc`).
if (startPart > 0 && startPart !== rootEnd) {
ret.dir = path.slice(0, startPart - 1);
} else ret.dir = ret.root;
return ret;
}