JS: Move some logic into StringAsPath

Author: asgerf

javascript/ql/lib/semmle/javascript/Paths.qll

@@ -96,37 +96,34 @@ private class ConsPath extends Path, TConsPath {
 private string pathRegex() { result = "(.*)(?:/|^)(([^/]*?)(\\.([^.]*))?)" }
 
 /**
- * A string value that represents a (relative or absolute) file system path.
- *
- * Each path string is associated with one or more root folders relative to
- * which the path may be resolved. For instance, paths inside a module are
- * usually resolved relative to the module's folder, with a default
- * lookup path as the fallback.
+ * Providers helper predicates for extracting parts of a path string.
  */
-abstract class PathString extends string {
+class StringAsPath extends string {
   bindingset[this]
-  PathString() { any() }
-
-  /** Gets a root folder relative to which this path can be resolved. */
-  abstract Folder getARootFolder();
+  StringAsPath() { any() }
 
   /** Gets the `i`th component of this path. */
+  bindingset[this]
   string getComponent(int i) { result = this.splitAt("/", i) }
 
   /** Gets the number of components of this path. */
+  bindingset[this]
   int getNumComponent() { result = count(int i | exists(this.getComponent(i))) }
 
   /** Gets the base name of the folder or file this path refers to. */
+  bindingset[this]
   string getBaseName() { result = this.regexpCapture(pathRegex(), 2) }
 
   /**
    * Gets stem of the folder or file this path refers to, that is, the prefix of its base name
    * up to (but not including) the last dot character if there is one, or the entire
    * base name if there is not
    */
+  bindingset[this]
   string getStem() { result = this.regexpCapture(pathRegex(), 3) }
 
   /** Gets the path of the parent folder of the folder or file this path refers to. */
+  bindingset[this]
   string getDirName() { result = this.regexpCapture(pathRegex(), 1) }
 
   /**
@@ -135,8 +132,26 @@ abstract class PathString extends string {
    *
    * Has no result if the base name does not contain a dot.
    */
+  bindingset[this]
   string getExtension() { result = this.regexpCapture(pathRegex(), 4) }
 
+}
+
+/**
+ * A string value that represents a (relative or absolute) file system path.
+ *
+ * Each path string is associated with one or more root folders relative to
+ * which the path may be resolved. For instance, paths inside a module are
+ * usually resolved relative to the module's folder, with a default
+ * lookup path as the fallback.
+ */
+abstract class PathString extends StringAsPath {
+  bindingset[this]
+  PathString() { any() }
+
+  /** Gets a root folder relative to which this path can be resolved. */
+  abstract Folder getARootFolder();
+
   /**
    * Gets the absolute path that the sub-path consisting of the first `n`
    * components of this path refers to when resolved relative to the

javascript/ql/lib/semmle/javascript/internal/paths/JSPaths.qll

@@ -6,22 +6,6 @@
 private import javascript
 private import semmle.javascript.TSConfig
 
-/**
- * Holds if `path` is relative, in the sense that it should be resolved relative to its enclosing folder.
- */
-bindingset[path]
-pragma[inline_late]
-predicate isRelativePath(string path) { path.regexpMatch("\\.\\.?(?:[/\\\\].*)?") }
-
-/**
- * Gets the NPM package name from the beginning of the given import path, e.g.
- * gets `foo` from `foo/bar`, and `@example/foo` from `@example/foo/bar`.
- */
-bindingset[path]
-string getPackagePrefixFromString(string path) {
-  result = path.regexpFind("^(@[^/\\\\]+[/\\\\])?[^@./\\\\][^/\\\\]*", _, _)
-}
-
 /**
  * Gets a folder name that is a common source folder name.
  */