[vala/wip/transform: 5/43] Move WhileStatement transformation into the code transformer

[Luca Bruno <lucabru src gnome org>]

commit 539a36d9dceea7eade968ca880939e19467f718a
Author: Luca Bruno <lucabru src gnome org>
Date:   Tue Aug 30 12:43:41 2011 +0200

    Move WhileStatement transformation into the code transformer

 vala/valacodetransformer.vala |   33 ++++++++++++++++++++++++-
 vala/valaflowanalyzer.vala    |   48 +++++++++++++++++++++++++++++++++++++
 vala/valawhilestatement.vala  |   53 +++++++++++++++++++++-------------------
 3 files changed, 108 insertions(+), 26 deletions(-)
---
diff --git a/vala/valacodetransformer.vala b/vala/valacodetransformer.vala
index e370e78..7f0b423 100644
--- a/vala/valacodetransformer.vala
+++ b/vala/valacodetransformer.vala
@@ -167,8 +167,39 @@ public class Vala.CodeTransformer : CodeVisitor {
 		label.accept_children (this);
 	}
 
+	bool always_true (Expression condition) {
+		var literal = condition as BooleanLiteral;
+		return (literal != null && literal.value);
+	}
+
+	bool always_false (Expression condition) {
+		var literal = condition as BooleanLiteral;
+		return (literal != null && !literal.value);
+	}
+
 	public override void visit_while_statement (WhileStatement stmt) {
-		stmt.accept_children (this);
+		// convert to simple loop
+
+		if (always_true (stmt.condition)) {
+			// do not generate if block if condition is always true
+		} else if (always_false (stmt.condition)) {
+			// do not generate if block if condition is always false
+			stmt.body.insert_statement (0, new BreakStatement (stmt.condition.source_reference));
+		} else {
+			var if_condition = new UnaryExpression (UnaryOperator.LOGICAL_NEGATION, stmt.condition, stmt.condition.source_reference);
+			var true_block = new Block (stmt.condition.source_reference);
+			true_block.add_statement (new BreakStatement (stmt.condition.source_reference));
+			var if_stmt = new IfStatement (if_condition, true_block, null, stmt.condition.source_reference);
+			stmt.body.insert_statement (0, if_stmt);
+		}
+
+		var loop = new Loop (stmt.body, stmt.source_reference);
+
+		var parent_block = (Block) stmt.parent_node;
+		parent_block.replace_statement (stmt, loop);
+
+		stmt.body.checked = false;
+		check (loop);
 	}
 
 	public override void visit_do_statement (DoStatement stmt) {
diff --git a/vala/valaflowanalyzer.vala b/vala/valaflowanalyzer.vala
index fffb17a..af4066a 100644
--- a/vala/valaflowanalyzer.vala
+++ b/vala/valaflowanalyzer.vala
@@ -736,6 +736,54 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		jump_stack.remove_at (jump_stack.size - 1);
 	}
 
+	public override void visit_while_statement (WhileStatement stmt) {
+		if (unreachable (stmt)) {
+			return;
+		}
+
+		var loop_block = new BasicBlock ();
+		jump_stack.add (new JumpTarget.continue_target (loop_block));
+		var after_loop_block = new BasicBlock ();
+		jump_stack.add (new JumpTarget.break_target (after_loop_block));
+
+		current_block.connect (loop_block);
+		current_block = loop_block;
+
+		// condition
+		loop_block.add_node (stmt.condition);
+		handle_errors (stmt.condition);
+
+		if (always_false (stmt.condition)) {
+			mark_unreachable ();
+		} else {
+			current_block = new BasicBlock ();
+			loop_block.connect (current_block);
+		}
+
+		if (!always_true (stmt.condition)) {
+			loop_block.connect (after_loop_block);
+		}
+
+		// loop block
+		stmt.body.accept (this);
+		// end of loop block reachable?
+		if (current_block != null) {
+			current_block.connect (loop_block);
+		}
+
+		// after loop block reachable?
+		if (after_loop_block.get_predecessors ().size == 0) {
+			// after loop block not reachable
+			mark_unreachable ();
+		} else {
+			// after loop block reachable
+			current_block = after_loop_block;
+		}
+
+		jump_stack.remove_at (jump_stack.size - 1);
+		jump_stack.remove_at (jump_stack.size - 1);
+	}
+
 	public override void visit_foreach_statement (ForeachStatement stmt) {
 		if (unreachable (stmt)) {
 			return;
diff --git a/vala/valawhilestatement.vala b/vala/valawhilestatement.vala
index 267e35e..84b66b5 100644
--- a/vala/valawhilestatement.vala
+++ b/vala/valawhilestatement.vala
@@ -81,38 +81,41 @@ public class Vala.WhileStatement : CodeNode, Statement {
 		body.accept (visitor);
 	}
 
-	bool always_true (Expression condition) {
-		var literal = condition as BooleanLiteral;
-		return (literal != null && literal.value);
-	}
-
-	bool always_false (Expression condition) {
-		var literal = condition as BooleanLiteral;
-		return (literal != null && !literal.value);
+	public override void replace_expression (Expression old_node, Expression new_node) {
+		if (condition == old_node) {
+			condition = new_node;
+		}
 	}
 
 	public override bool check (CodeContext context) {
-		// convert to simple loop
-
-		if (always_true (condition)) {
-			// do not generate if block if condition is always true
-		} else if (always_false (condition)) {
-			// do not generate if block if condition is always false
-			body.insert_statement (0, new BreakStatement (condition.source_reference));
-		} else {
-			var if_condition = new UnaryExpression (UnaryOperator.LOGICAL_NEGATION, condition, condition.source_reference);
-			var true_block = new Block (condition.source_reference);
-			true_block.add_statement (new BreakStatement (condition.source_reference));
-			var if_stmt = new IfStatement (if_condition, true_block, null, condition.source_reference);
-			body.insert_statement (0, if_stmt);
+		if (checked) {
+			return !error;
+		}
+
+		checked = true;
+
+		condition.target_type = context.analyzer.bool_type.copy ();
+
+		condition.check (context);
+
+		if (condition.error) {
+			/* if there was an error in the condition, skip this check */
+			error = true;
+			return false;
 		}
 
-		var loop = new Loop (body, source_reference);
+		if (condition.value_type == null || !condition.value_type.compatible (context.analyzer.bool_type)) {
+			error = true;
+			Report.error (condition.source_reference, "Condition must be boolean");
+			return false;
+		}
 
-		var parent_block = (Block) parent_node;
-		parent_block.replace_statement (this, loop);
+		if (!body.check (context)) {
+			error = true;
+			return false;
+		}
 
-		return loop.check (context);
+		return !error;
 	}
 }