@tybys/wasm-util
Version:
WASI polyfill for browser and some wasm util
169 lines (168 loc) • 5.91 kB
JavaScript
import { validateString } from "./util.mjs";
const CHAR_DOT = 46; /* . */
const CHAR_FORWARD_SLASH = 47; /* / */
function isPosixPathSeparator(code) {
return code === CHAR_FORWARD_SLASH;
}
function normalizeString(path, allowAboveRoot, separator, isPathSeparator) {
let res = '';
let lastSegmentLength = 0;
let lastSlash = -1;
let dots = 0;
let code = 0;
for (let i = 0; i <= path.length; ++i) {
if (i < path.length) {
code = path.charCodeAt(i);
}
else if (isPathSeparator(code)) {
break;
}
else {
code = CHAR_FORWARD_SLASH;
}
if (isPathSeparator(code)) {
if (lastSlash === i - 1 || dots === 1) {
// NOOP
}
else if (dots === 2) {
if (res.length < 2 || lastSegmentLength !== 2 ||
res.charCodeAt(res.length - 1) !== CHAR_DOT ||
res.charCodeAt(res.length - 2) !== CHAR_DOT) {
if (res.length > 2) {
const lastSlashIndex = res.indexOf(separator);
if (lastSlashIndex === -1) {
res = '';
lastSegmentLength = 0;
}
else {
res = res.slice(0, lastSlashIndex);
lastSegmentLength =
res.length - 1 - res.indexOf(separator);
}
lastSlash = i;
dots = 0;
continue;
}
else if (res.length !== 0) {
res = '';
lastSegmentLength = 0;
lastSlash = i;
dots = 0;
continue;
}
}
if (allowAboveRoot) {
res += res.length > 0 ? `${separator}..` : '..';
lastSegmentLength = 2;
}
}
else {
if (res.length > 0) {
res += `${separator}${path.slice(lastSlash + 1, i)}`;
}
else {
res = path.slice(lastSlash + 1, i);
}
lastSegmentLength = i - lastSlash - 1;
}
lastSlash = i;
dots = 0;
}
else if (code === CHAR_DOT && dots !== -1) {
++dots;
}
else {
dots = -1;
}
}
return res;
}
export function resolve(...args) {
let resolvedPath = '';
let resolvedAbsolute = false;
for (let i = args.length - 1; i >= -1 && !resolvedAbsolute; i--) {
const path = i >= 0 ? args[i] : '/';
validateString(path, 'path');
// Skip empty entries
if (path.length === 0) {
continue;
}
resolvedPath = `${path}/${resolvedPath}`;
resolvedAbsolute = path.charCodeAt(0) === CHAR_FORWARD_SLASH;
}
// At this point the path should be resolved to a full absolute path, but
// handle relative paths to be safe (might happen when process.cwd() fails)
// Normalize the path
resolvedPath = normalizeString(resolvedPath, !resolvedAbsolute, '/', isPosixPathSeparator);
if (resolvedAbsolute) {
return `/${resolvedPath}`;
}
return resolvedPath.length > 0 ? resolvedPath : '.';
}
export function relative(from, to) {
validateString(from, 'from');
validateString(to, 'to');
if (from === to)
return '';
// Trim leading forward slashes.
from = resolve(from);
to = resolve(to);
if (from === to)
return '';
const fromStart = 1;
const fromEnd = from.length;
const fromLen = fromEnd - fromStart;
const toStart = 1;
const toLen = to.length - toStart;
// Compare paths to find the longest common path from root
const length = (fromLen < toLen ? fromLen : toLen);
let lastCommonSep = -1;
let i = 0;
for (; i < length; i++) {
const fromCode = from.charCodeAt(fromStart + i);
if (fromCode !== to.charCodeAt(toStart + i)) {
break;
}
else if (fromCode === CHAR_FORWARD_SLASH) {
lastCommonSep = i;
}
}
if (i === length) {
if (toLen > length) {
if (to.charCodeAt(toStart + i) === CHAR_FORWARD_SLASH) {
// We get here if `from` is the exact base path for `to`.
// For example: from='/foo/bar'; to='/foo/bar/baz'
return to.slice(toStart + i + 1);
}
if (i === 0) {
// We get here if `from` is the root
// For example: from='/'; to='/foo'
return to.slice(toStart + i);
}
}
else if (fromLen > length) {
if (from.charCodeAt(fromStart + i) === CHAR_FORWARD_SLASH) {
// We get here if `to` is the exact base path for `from`.
// For example: from='/foo/bar/baz'; to='/foo/bar'
lastCommonSep = i;
}
else if (i === 0) {
// We get here if `to` is the root.
// For example: from='/foo/bar'; to='/'
lastCommonSep = 0;
}
}
}
let out = '';
// Generate the relative path based on the path difference between `to`
// and `from`.
for (i = fromStart + lastCommonSep + 1; i <= fromEnd; ++i) {
if (i === fromEnd ||
from.charCodeAt(i) === CHAR_FORWARD_SLASH) {
out += out.length === 0 ? '..' : '/..';
}
}
// Lastly, append the rest of the destination (`to`) path that comes after
// the common path parts.
return `${out}${to.slice(toStart + lastCommonSep)}`;
}