Ruby: Simplify getValueText logic for StringlikeLiterals

Author: hvitved

ruby/ql/lib/codeql/ruby/ast/Literal.qll

@@ -10,15 +10,7 @@ private import codeql.ruby.controlflow.CfgNodes
  *
  * This is the QL root class for all literals.
  */
-class Literal extends Expr, TLiteral {
-  /**
-   * Gets the source text for this literal, if this is a simple literal.
-   *
-   * For complex literals, such as arrays, hashes, and strings with
-   * interpolations, this predicate has no result.
-   */
-  override string getValueText() { none() }
-}
+class Literal extends Expr, TLiteral { }
 
 /**
  * A numeric literal, i.e. an integer, floating-point, rational, or complex
@@ -411,17 +403,6 @@ class StringlikeLiteral extends Literal, TStringlikeLiteral {
     result = ""
   }
 
-  override string getValueText() {
-    forall(StringComponent c | c = this.getComponent(_) |
-      not c instanceof StringInterpolationComponent
-    ) and
-    result =
-      concat(StringComponent c, int i | c = this.getComponent(i) | c.getValueText() order by i)
-    or
-    exists(this.getComponent(_)) and
-    result = this.getAControlFlowNode().(ExprNodes::StringlikeLiteralCfgNode).getValueText()
-  }
-
   override string toString() {
     exists(string full, string summary |
       full =

ruby/ql/lib/codeql/ruby/controlflow/CfgNodes.qll

@@ -485,7 +485,7 @@ module ExprNodes {
     final override StringlikeLiteral getExpr() { result = super.getExpr() }
 
     /** Gets the `n`th component of this `StringlikeLiteral` */
-    StringComponentCfgNode getComponent(int n) { result.getNode() = e.getComponent(n) }
+    StringComponentCfgNode getComponent(int n) { e.hasCfgChild(e.getComponent(n), this, result) }
 
     /** Gets a component of this `StringlikeLiteral` */
     StringComponentCfgNode getAComponent() { result = this.getComponent(_) }
@@ -494,26 +494,13 @@ module ExprNodes {
     // if all interpolations have a known string value, we will get a result
     language[monotonicAggregates]
     override string getValueText() {
-      result = e.getValueText()
-      or
       result =
-        concat(StringComponent c, int i |
-          c = e.getComponent(i)
+        concat(StringComponentCfgNode c, int i |
+          c = this.getComponent(i)
         |
-          getComponentValueText(c) order by i
+          c.getValueText() order by i
         )
     }
-
-    /**
-     * Get the `ValueText()` of a `StringComponent`.
-     * If the component has a CFG node, defer to that (in order to resolve variables in interpolations).
-     * Otherwise, defer to the AST node.
-     */
-    private string getComponentValueText(StringComponent c) {
-      exists(StringComponentCfgNode n | n.getNode() = c | result = n.getValueText())
-      or
-      not exists(StringComponentCfgNode n | n.getNode() = c) and result = c.getValueText()
-    }
   }
 
   /** A control-flow node that wraps a `StringLiteral` AST expression. */

ruby/ql/test/library-tests/ast/ValueText.expected

@@ -614,7 +614,6 @@
 | modules/modules.rb:55:8:55:30 | "module Foo::Bar again" | module Foo::Bar again |
 | modules/modules.rb:56:17:56:17 | 4 | 4 |
 | modules/toplevel.rb:1:6:1:12 | "world" | world |
-| modules/toplevel.rb:3:12:3:16 | "!!!" | !!! |
 | modules/toplevel.rb:5:14:5:20 | "hello" | hello |
 | operations/operations.rb:3:5:3:5 | 0 | 0 |
 | operations/operations.rb:4:5:4:5 | 0 | 0 |