1 files changed, 116 insertions, 0 deletions
diff --git a/std/fs/path/utils.ts b/std/fs/path/utils.ts
new file mode 100644
index 000000000..7a4cd7299
--- /dev/null
+++ b/std/fs/path/utils.ts
@@ -0,0 +1,116 @@
+// Copyright the Browserify authors. MIT License.
+// Ported from https://github.com/browserify/path-browserify/
+
+import { FormatInputPathObject } from "./interface.ts";
+import {
+  CHAR_UPPERCASE_A,
+  CHAR_LOWERCASE_A,
+  CHAR_UPPERCASE_Z,
+  CHAR_LOWERCASE_Z,
+  CHAR_DOT,
+  CHAR_FORWARD_SLASH,
+  CHAR_BACKWARD_SLASH
+} from "./constants.ts";
+
+export function assertPath(path: string): void {
+  if (typeof path !== "string") {
+    throw new TypeError(
+      `Path must be a string. Received ${JSON.stringify(path)}`
+    );
+  }
+}
+
+export function isPosixPathSeparator(code: number): boolean {
+  return code === CHAR_FORWARD_SLASH;
+}
+
+export function isPathSeparator(code: number): boolean {
+  return isPosixPathSeparator(code) || code === CHAR_BACKWARD_SLASH;
+}
+
+export function isWindowsDeviceRoot(code: number): boolean {
+  return (
+    (code >= CHAR_LOWERCASE_A && code <= CHAR_LOWERCASE_Z) ||
+    (code >= CHAR_UPPERCASE_A && code <= CHAR_UPPERCASE_Z)
+  );
+}
+
+// Resolves . and .. elements in a path with directory names
+export function normalizeString(
+  path: string,
+  allowAboveRoot: boolean,
+  separator: string,
+  isPathSeparator: (code: number) => boolean
+): string {
+  let res = "";
+  let lastSegmentLength = 0;
+  let lastSlash = -1;
+  let dots = 0;
+  let code: number;
+  for (let i = 0, len = path.length; i <= len; ++i) {
+    if (i < len) 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 (lastSlash !== i - 1 && 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.lastIndexOf(separator);
+            if (lastSlashIndex === -1) {
+              res = "";
+              lastSegmentLength = 0;
+            } else {
+              res = res.slice(0, lastSlashIndex);
+              lastSegmentLength = res.length - 1 - res.lastIndexOf(separator);
+            }
+            lastSlash = i;
+            dots = 0;
+            continue;
+          } else if (res.length === 2 || res.length === 1) {
+            res = "";
+            lastSegmentLength = 0;
+            lastSlash = i;
+            dots = 0;
+            continue;
+          }
+        }
+        if (allowAboveRoot) {
+          if (res.length > 0) res += `${separator}..`;
+          else res = "..";
+          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 _format(
+  sep: string,
+  pathObject: FormatInputPathObject
+): string {
+  const dir: string | undefined = pathObject.dir || pathObject.root;
+  const base: string =
+    pathObject.base || (pathObject.name || "") + (pathObject.ext || "");
+  if (!dir) return base;
+  if (dir === pathObject.root) return dir + base;
+  return dir + sep + base;
+}