Unified: Add a debug query to view the AST as a graph.

unified/ql/lib/codeql/unified/internal/dev/debugAst.ql

@@ -0,0 +1,50 @@
+/**
+ * @name Pretty print AST as graph
+ * @description Debug the AST by printing it as a graph.
+ * @id unified/debug-ast
+ * @kind graph
+ */
+
+import unified
+
+private predicate skip(AstNode e) { e instanceof Modifier }
+
+AstNode getChild(AstNode n, int index) {
+  result.getParent() = n and
+  result.getParentIndex() = index and
+  not skip(n) and
+  not skip(result)
+}
+
+predicate relevant(AstNode n) {
+  n.getLocation().getFile().getBaseName() = "CLI.swift" and
+  n.getLocation().getStartLine() = [98 .. 120] and
+  not skip(n)
+}
+
+// Add additional node info here
+string tag(AstNode n) { none() }
+
+query predicate nodes(AstNode n, string key, string val) {
+  key = "semmle.label" and
+  relevant(n) and
+  val = concat(string t | t = tag(n)) + " " + n.toString()
+}
+
+// Add additional edge info here
+string etag(AstNode child, AstNode parent) {
+  exists(string name, int i, string arg |
+    PrintAst::getChild(parent, name, i) = child and
+    result = name + arg and
+    if i = -1 then arg = "()" else arg = "(" + i.toString() + ")"
+  )
+}
+
+query predicate edges(AstNode pred, AstNode succ, string attr, string val) {
+  attr = "semmle.label" and
+  relevant(succ) and
+  exists(int i |
+    pred = getChild(succ, i) and
+    val = i + " " + concat(string t | t = etag(pred, succ) | t, ", ")
+  )
+}