Replace getEncodedFile with shared getFileBySourceArchiveName predicate

While also making it work with paths for databases created on Windows.

javascript/ql/src/IDEContextual.qll

@@ -0,0 +1,22 @@
+/*
+ * Provides shared predicates related to contextual queries in the code viewer.
+ */
+
+import semmle.files.FileSystem
+
+/**
+ * Returns the `File` matching the given source file name as encoded by the VS
+ * Code extension.
+ */
+cached
+File getFileBySourceArchiveName(string name) {
+  // The name provided for a file in the source archive by the VS Code extension
+  // has some differences from the absolute path in the database:
+  // 1. colons are replaced by underscores
+  // 2. there's a leading slash, even for Windows paths: "C:/foo/bar" ->
+  //    "/C_/foo/bar"
+  // 3. double slashes in UNC prefixes are replaced with a single slash
+  // We can handle 2 and 3 together by unconditionally adding a leading slash
+  // before replacing double slashes.
+  name = ("/" + result.getAbsolutePath().replaceAll(":", "_")).replaceAll("//", "/")
+}

javascript/ql/src/definitions.qll

@@ -4,6 +4,7 @@
  */
 
 import javascript
+import IDEContextual
 private import Declarations.Declarations
 
 /**
@@ -178,11 +179,3 @@ ASTNode definitionOf(Locatable e, string kind) {
   or
   jsdocTypeLookup(e, result, kind)
 }
-
-/**
- * Returns an appropriately encoded version of a filename `name`
- * passed by the VS Code extension in order to coincide with the
- * output of `.getFile()` on locatable entities.
- */
-cached
-File getEncodedFile(string name) { result.getAbsolutePath().replaceAll(":", "_") = name }

javascript/ql/src/localDefinitions.ql

@@ -12,5 +12,5 @@ import definitions
 external string selectedSourceFile();
 
 from Locatable e, ASTNode def, string kind
-where def = definitionOf(e, kind) and e.getFile() = getEncodedFile(selectedSourceFile())
+where def = definitionOf(e, kind) and e.getFile() = getFileBySourceArchiveName(selectedSourceFile())
 select e, def, kind

javascript/ql/src/localReferences.ql

@@ -12,5 +12,6 @@ import definitions
 external string selectedSourceFile();
 
 from Locatable e, ASTNode def, string kind
-where def = definitionOf(e, kind) and def.getFile() = getEncodedFile(selectedSourceFile())
+where
+  def = definitionOf(e, kind) and def.getFile() = getFileBySourceArchiveName(selectedSourceFile())
 select e, def, kind

javascript/ql/src/printAst.ql

@@ -23,6 +23,6 @@ class PrintAstConfigurationOverride extends PrintAstConfiguration {
    */
   override predicate shouldPrint(Locatable e, Location l) {
     super.shouldPrint(e, l) and
-    l.getFile() = getEncodedFile(selectedSourceFile())
+    l.getFile() = getFileBySourceArchiveName(selectedSourceFile())
   }
 }