Fix forward declaration procedure parsing

- Fix forward declaration procedures not parsing correctly if they are not followed by an AST term. This seems to only be an issue in interpreter mode as far as was tested.
- Add comments to clarify proc keyword rewriting logic.

Author: Pieter12345

src/main/java/com/laytonsmith/core/compiler/keywords/ProcKeyword.java

@@ -28,64 +28,93 @@ public int process(List<ParseTree> list, int keywordPosition) throws ConfigCompi
 		if(list.get(keywordPosition).getData() instanceof CKeyword) {
 			// It's a lone keyword, so we expect some function to follow, which is the proc name + variables
 			FileOptions options = list.get(keywordPosition).getFileOptions();
+
+			// Validate minimal required number of nodes.
 			if(list.size() <= keywordPosition + 1) {
 				throw new ConfigCompileException("Unexpected keyword", list.get(keywordPosition).getTarget());
 			}
+
+			/*
+			 * Parse:
+			 *     "proc _procName(params) { code }" to "proc(_procName, params, code)". Params and code are optional.
+			 *     "proc _procName(params)" to "proc(_procName, params, noop())". Params are optional.
+			 *     "proc _procName" to "get_proc(_procName)".
+			 */
 			if(list.get(keywordPosition + 1).getData() instanceof CFunction) {
+
+				// Create proc function node.
 				ParseTree procNode = new ParseTree(new CFunction(
 						DataHandling.proc.NAME, list.get(keywordPosition).getTarget()), options);
 				procNode.getNodeModifiers().merge(list.get(keywordPosition).getNodeModifiers());
+
+				// Add proc name to proc function node. Proc name node is currently a function node.
 				procNode.addChild(new ParseTree(new CString(list.get(keywordPosition + 1).getData().val(),
 						list.get(keywordPosition + 1).getTarget()), options));
-				// Grab the functions children, and put them on the stack
+
+				// Move proc name function node children to proc function node.
 				for(ParseTree child : list.get(keywordPosition + 1).getChildren()) {
 					procNode.addChild(child);
 				}
-				boolean forwardDeclaration = false;
-				if(list.size() > keywordPosition + 2) {
-					if(list.get(keywordPosition + 2).getData() instanceof CFunction cf
-							&& com.laytonsmith.core.functions.Compiler.__cbrace__.NAME.equals(cf.val())) {
-						validateCodeBlock(list.get(keywordPosition + 2), "Expected braces to follow proc definition");
-						procNode.addChild(getArgumentOrNoop(list.get(keywordPosition + 2)));
-					} else {
-						// Forward declaration, add a noop "implementation"
-						forwardDeclaration = true;
-						ParseTree statement = new ParseTree(new CFunction(Compiler.__statements__.NAME, Target.UNKNOWN),
-								list.get(keywordPosition + 1).getFileOptions(), true);
-						statement.addChild(new ParseTree(new CFunction(Meta.noop.NAME, Target.UNKNOWN),
-								list.get(keywordPosition + 1).getFileOptions(), true));
-						procNode.addChild(statement);
-					}
+
+				// Get code block from __cbrace__ function node. Define as forward declaration if code block is missing.
+				if(list.size() > keywordPosition + 2
+						&& list.get(keywordPosition + 2).getData() instanceof CFunction cf
+						&& com.laytonsmith.core.functions.Compiler.__cbrace__.NAME.equals(cf.val())) {
+
+					// Validate code block and add to proc function node.
+					validateCodeBlock(list.get(keywordPosition + 2), "Expected braces to follow proc definition");
+					procNode.addChild(getArgumentOrNoop(list.get(keywordPosition + 2)));
+
+					// Remove processed nodes from AST.
+					list.remove(keywordPosition); // Remove keyword node.
+					list.remove(keywordPosition); // Remove proc name function node (with proc parameters).
+					list.remove(keywordPosition); // Remove __cbrace__ function node.
 				} else {
-					throw new ConfigCompileException("Expected braces to follow proc definition", list.get(keywordPosition + 1).getTarget());
-				}
-				list.remove(keywordPosition); // Remove the keyword
-				list.remove(keywordPosition); // Remove the function definition
-				if(!forwardDeclaration) {
-					list.remove(keywordPosition); // Remove the cbrace
+
+					// Define as forward declaration by add a "noop()" as code block.
+					ParseTree statement = new ParseTree(new CFunction(Compiler.__statements__.NAME, Target.UNKNOWN),
+							list.get(keywordPosition + 1).getFileOptions(), true);
+					statement.addChild(new ParseTree(new CFunction(Meta.noop.NAME, Target.UNKNOWN),
+							list.get(keywordPosition + 1).getFileOptions(), true));
+					procNode.addChild(statement);
+
+					// Remove processed nodes from AST.
+					list.remove(keywordPosition); // Remove keyword node.
+					list.remove(keywordPosition); // Remove proc name function node (with proc parameters).
 				}
-				list.add(keywordPosition, procNode); // Add in the new proc definition
+
+				// Add proc function node to AST.
+				list.add(keywordPosition, procNode);
+
 			} else if(list.get(keywordPosition + 1).getData() instanceof CBareString name) {
-				// get_proc rewrite
-				list.remove(keywordPosition);
-				list.remove(keywordPosition);
+
+				// Parse "proc _procName" to "get_proc(_procName)".
+				list.remove(keywordPosition); // Remove keyword node.
+				list.remove(keywordPosition); // Remove proc name node.
+
+				// Add get_proc function node with proc name child node to AST.
 				ParseTree getProc = new ParseTree(new CFunction(DataHandling.get_proc.NAME, Target.UNKNOWN), options, true);
 				getProc.addChild(new ParseTree(new CString(name.val(), name.getTarget()), options));
 				list.add(keywordPosition, getProc);
+
 			} else {
+
+				// Proc keyword used incorrectly.
 				throw new ConfigCompileException("Unexpected use of \"proc\" keyword", list.get(keywordPosition).getTarget());
 			}
 
 		} else if(nodeIsProcFunction(list.get(keywordPosition))) {
-			// It's the functional usage, possibly followed by a cbrace. If so, pull the cbrace in, and that's it
-			if(list.size() > keywordPosition + 1) {
-				if(isValidCodeBlock(list.get(keywordPosition + 1))) {
-					list.get(keywordPosition).addChild(getArgumentOrNoop(list.get(keywordPosition + 1)));
-					list.remove(keywordPosition + 1);
-				}
+
+			// Parse "proc(_procName, params) { code }" to "proc(_procName, params, code)". Params are optional.
+			if(list.size() > keywordPosition + 1 && isValidCodeBlock(list.get(keywordPosition + 1))) {
+
+				// Pull in __cbrace__ function node as proc function node code block.
+				list.get(keywordPosition).addChild(getArgumentOrNoop(list.get(keywordPosition + 1)));
+				list.remove(keywordPosition + 1); // Remove __cbrace__ function node.
 			}
 		} else {
-			// Random keyword in the middle of nowhere
+
+			// Random proc keyword in the middle of nowhere.
 			throw new ConfigCompileException("Unexpected use of \"proc\" keyword", list.get(keywordPosition).getTarget());
 		}
 		return keywordPosition;