PS: Move a bunch of predicates into ScriptBlock.

powershell/ql/lib/semmle/code/powershell/ScriptBlock.qll

@@ -10,7 +10,7 @@ class ScriptBlock extends @script_block, Ast {
     else result = "{...}"
   }
 
-  override SourceLocation getLocation() { script_block_location(this, result) }
+  override Location getLocation() { script_block_location(this, result) }
 
   int getNumUsings() { script_block(this, result, _, _, _, _) }
 
@@ -51,6 +51,42 @@ class ScriptBlock extends @script_block, Ast {
   ModuleSpecification getAModuleSpecification() { result = this.getModuleSpecification(_) }
 
   final override Scope getEnclosingScope() { result = this }
+
+  /**
+   * Gets the `i`'th paramter in this scope.
+   *
+   * This may be both function paramters and parameter block parameters.
+   */
+  Parameter getParameter(int i) {
+    exists(Function func |
+      func.getBody() = this and
+      result = func.getParameter(i)
+    )
+    or
+    this.isTopLevel() and
+    result = this.getParamBlock().getParameter(i)
+  }
+
+  /**
+   * Gets a paramter in this scope.
+   *
+   * This may be both function parameters and parameter block parameters.
+   */
+  Parameter getAParameter() { result = this.getParameter(_) }
+
+  Parameter getThisParameter() {
+    exists(Function func |
+      func.getBody() = this and
+      result = func.getThisParameter()
+    )
+  }
+
+  /** Gets the number of function parameters. */
+  final int getNumberOfParameters() { result = count(this.getAParameter()) }
+
+  final Parameter getParameterExcludingPiplines(int i) {
+    result = this.getParamBlock().getParameterExcludingPiplines(i)
+  }
 }
 
 /** A `process` block. */
@@ -69,3 +105,7 @@ class ProcessBlock extends NamedBlock {
     result = scriptBlock.getEnclosingFunction().getAParameter()
   }
 }
+
+class TopLevelScriptBlock extends ScriptBlock {
+  TopLevelScriptBlock() { this.isTopLevel() }
+}

powershell/ql/lib/semmle/code/powershell/controlflow/internal/Scope.qll

@@ -14,33 +14,7 @@ Scope scopeOf(Ast n) {
  * A variable scope. This is either a top-level (file), a module, a class,
  * or a callable.
  */
-class Scope extends Ast, @script_block {
+class Scope extends Ast, ScriptBlock {
   /** Gets the outer scope, if any. */
   Scope getOuterScope() { result = scopeOf(this) }
-
-  /**
-   * Gets the `i`'th paramter in this scope.
-   *
-   * This may be both function paramters and parameter block parameters.
-   */
-  Parameter getParameter(int i) {
-    exists(Function func |
-      func.getBody() = this and
-      result = func.getParameter(i)
-    )
-  }
-
-  /**
-   * Gets a paramter in this scope.
-   *
-   * This may be both function paramters and parameter block parameters.
-   */
-  Parameter getAParameter() { result = this.getParameter(_) }
-
-  Parameter getThisParameter() {
-    exists(Function func |
-      func.getBody() = this and
-      result = func.getThisParameter()
-    )
-  }
 }