From 619f1f05c82f57fc1bcab971531620507614dffd Mon Sep 17 00:00:00 2001
From: Hackerpilot <briancschott@gmail.com>
Date: Mon, 17 Feb 2014 21:10:23 -0800
Subject: [PATCH] Fix #111

---
 analysis/del.d   |   2 +-
 analysis/range.d | 104 +++++++++++++++++++++++++++++++++++++++++++++++
 analysis/run.d   |   6 ++-
 3 files changed, 110 insertions(+), 2 deletions(-)
 create mode 100644 analysis/range.d

diff --git a/analysis/del.d b/analysis/del.d
index 8cd3646..04aa33f 100644
--- a/analysis/del.d
+++ b/analysis/del.d
@@ -23,7 +23,7 @@ class DeleteCheck : BaseAnalyzer
 
 	override void visit(DeleteExpression d)
 	{
-		addErrorMessage(d.line, d.column, "Avoid using the deprecated delete keyword");
+		addErrorMessage(d.line, d.column, "Avoid using the delete keyword");
 		d.accept(this);
 	}
 }
diff --git a/analysis/range.d b/analysis/range.d
new file mode 100644
index 0000000..556acf8
--- /dev/null
+++ b/analysis/range.d
@@ -0,0 +1,104 @@
+//          Copyright Brian Schott (Sir Alaran) 2014.
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+
+module analysis.range;
+
+import stdx.d.ast;
+import stdx.d.lexer;
+import analysis.base;
+
+/**
+ * Checks for .. expressions where the left side is larger than the right. This
+ * is almost always a mistake.
+ */
+class BackwardsRangeCheck : BaseAnalyzer
+{
+	alias visit = BaseAnalyzer.visit;
+
+	bool hasLeft;
+	bool hasRight;
+	long left;
+	long right;
+	size_t column;
+	size_t line;
+	enum State { ignore, left, right }
+	State state = State.ignore;
+
+	this(string fileName)
+	{
+		super(fileName);
+	}
+
+	override void visit(ForeachStatement foreachStatement)
+	{
+		if (foreachStatement.low !is null && foreachStatement.high !is null)
+		{
+			import std.string;
+			state = State.left;
+			foreachStatement.low.accept(this);
+			state = State.right;
+			foreachStatement.high.accept(this);
+			state = State.ignore;
+			if (hasLeft && hasRight && left > right)
+			{
+				string message = format(
+					"%d is larger than %d. Did you mean to use 'foreach_reverse( ... ; %d .. %d)'?",
+					left, right, right, left);
+				addErrorMessage(line, this.column, message);
+			}
+			hasLeft = false;
+			hasRight = false;
+			foreachStatement.accept(this);
+		}
+	}
+
+	override void visit(UnaryExpression unary)
+	{
+		if (state != State.ignore && unary.primaryExpression is null)
+			return;
+		else
+			unary.accept(this);
+	}
+
+	override void visit(PrimaryExpression primary)
+	{
+		import std.conv;
+		if (state == State.ignore || !isNumberLiteral(primary.primary.type))
+			return;
+		if (state == State.left)
+		{
+			line = primary.primary.line;
+			column = primary.primary.column;
+			left = to!long(primary.primary.text);
+			hasLeft = true;
+		}
+		else
+		{
+			right = to!long(primary.primary.text);
+			hasRight = true;
+		}
+	}
+
+	override void visit(SliceExpression sliceExpression)
+	{
+		import std.stdio;
+		state = State.left;
+		sliceExpression.lower.accept(this);
+		state = State.right;
+		sliceExpression.upper.accept(this);
+		state = State.ignore;
+		if (hasLeft && hasRight && left > right)
+		{
+			import std.string;
+			string message = format(
+				"%d is larger than %d. This slice is likely incorrect.",
+				left, right);
+			addErrorMessage(line, this.column, message);
+		}
+		hasLeft = false;
+		hasRight = false;
+		sliceExpression.accept(this);
+	}
+}
diff --git a/analysis/run.d b/analysis/run.d
index 12d935f..3b5bad6 100644
--- a/analysis/run.d
+++ b/analysis/run.d
@@ -19,6 +19,7 @@ import analysis.del;
 import analysis.fish;
 import analysis.numbers;
 import analysis.objectconst;
+import analysis.range;
 
 void messageFunction(string fileName, size_t line, size_t column, string message,
 	bool isError)
@@ -79,9 +80,12 @@ void analyze(File output, string[] fileNames, bool staticAnalyze = true)
 		auto objConst = new ObjectConstCheck(fileName);
 		objConst.visit(m);
 
+		auto backwardsRange = new BackwardsRangeCheck(fileName);
+		backwardsRange.visit(m);
+
 		foreach (message; sort(chain(enums.messages, style.messages,
 			pokemon.messages, del.messages, fish.messages, numbers.messages,
-			objConst.messages).array))
+			objConst.messages, backwardsRange.messages).array))
 		{
 			writeln(message);
 		}