From 1174f2e9bd7a320291b5c2dfe3cd730a93ade084 Mon Sep 17 00:00:00 2001
From: "Fuji, Goro" <g.psy.va@gmail.com>
Date: Sun, 25 Aug 2013 10:51:45 +0900
Subject: [PATCH 1/3] allow `object as string`

as a (logically) shortcut of `o != null ? o.toString() : "null"`
---
 src/expression.jsx             |  6 +++++-
 src/jsemitter.jsx              |  5 +++++
 t/run/346.object-as-string.jsx | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 t/run/346.object-as-string.jsx

diff --git a/src/expression.jsx b/src/expression.jsx
index e334d09a..eb6ecab8 100644
--- a/src/expression.jsx
+++ b/src/expression.jsx
@@ -989,7 +989,11 @@ class AsExpression extends UnaryExpression {
 		// possibly unsafe conversions
 		var exprType = this._expr.getType().resolveIfNullable();
 		var success = false;
-		if (exprType.equals(Type.nullType)) {
+		if (this._type.equals(Type.stringType)) {
+			// ok: any => string
+			success = true;
+		}
+		else if (exprType.equals(Type.nullType)) {
 			if (this._type instanceof ObjectType || this._type instanceof FunctionType) {
 				// ok
 				success = true;
diff --git a/src/jsemitter.jsx b/src/jsemitter.jsx
index 8099c935..f5af8ea7 100644
--- a/src/jsemitter.jsx
+++ b/src/jsemitter.jsx
@@ -1648,6 +1648,11 @@ class _AsExpressionEmitter extends _ExpressionEmitter {
 				new _AsNoConvertExpressionEmitter(this._emitter, new AsNoConvertExpression(this._expr.getToken(), this._expr.getExpr(), this._expr.getType())).emit(outerOpPrecedence);
 				return;
 			}
+			if (destType.equals(Type.stringType)) {
+				var prec = _AdditiveExpressionEmitter._operatorPrecedence;
+				this._emitWithParens(outerOpPrecedence, prec, prec, null, " + \"\"");
+				return;
+			}
 		}
 		if (srcType.resolveIfNullable().equals(Type.booleanType)) {
 			// from boolean
diff --git a/t/run/346.object-as-string.jsx b/t/run/346.object-as-string.jsx
new file mode 100644
index 00000000..c3804d3f
--- /dev/null
+++ b/t/run/346.object-as-string.jsx
@@ -0,0 +1,18 @@
+/*EXPECTED
+foo
+null
+*/
+
+class _Main {
+  override function toString() : string {
+    return "foo";
+  }
+
+  static function main(args : string[]) : void {
+    var object = new _Main;
+    log object as string;
+    object = null;
+    log object as string;
+  }
+}
+// vim: set expandtab tabstop=2 shiftwidth=2 ft=jsx:

From 6b7f7367513f0a5132887354c155b6909f6aa6c6 Mon Sep 17 00:00:00 2001
From: "Fuji, Goro" <g.psy.va@gmail.com>
Date: Sun, 25 Aug 2013 11:06:28 +0900
Subject: [PATCH 2/3] there's no reason to allow `null as string`

tested in t/compile_error/144.null-as-primitive.jsx
---
 src/expression.jsx | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/expression.jsx b/src/expression.jsx
index eb6ecab8..1ed12212 100644
--- a/src/expression.jsx
+++ b/src/expression.jsx
@@ -989,15 +989,14 @@ class AsExpression extends UnaryExpression {
 		// possibly unsafe conversions
 		var exprType = this._expr.getType().resolveIfNullable();
 		var success = false;
-		if (this._type.equals(Type.stringType)) {
-			// ok: any => string
-			success = true;
-		}
-		else if (exprType.equals(Type.nullType)) {
+		if (exprType.equals(Type.nullType)) {
 			if (this._type instanceof ObjectType || this._type instanceof FunctionType) {
 				// ok
 				success = true;
 			}
+		} else if (this._type.equals(Type.stringType)) {
+			// ok: any-but-null => string
+			success = true;
 		} else if (exprType instanceof PrimitiveType) {
 			if (this._type instanceof PrimitiveType) {
 				// ok: primitive => primitive

From b9dc1461bd46d4b8a7a4f65a3242ef0091f62192 Mon Sep 17 00:00:00 2001
From: "Fuji, Goro" <g.psy.va@gmail.com>
Date: Sun, 25 Aug 2013 12:11:38 +0900
Subject: [PATCH 3/3] add another test for `object as string`

---
 t/run/347.generic-as-string.jsx | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 t/run/347.generic-as-string.jsx

diff --git a/t/run/347.generic-as-string.jsx b/t/run/347.generic-as-string.jsx
new file mode 100644
index 00000000..d882777f
--- /dev/null
+++ b/t/run/347.generic-as-string.jsx
@@ -0,0 +1,29 @@
+/*EXPECTED
+C: foo
+C: _Main
+C: null
+*/
+
+class C.<T> {
+  var value : T;
+  function constructor(value : T) {
+    this.value = value;
+  }
+
+  function debugLog() : void {
+    log "C: " + this.value as string;
+  }
+}
+
+class _Main {
+  override function toString() : string {
+    return "_Main";
+  }
+
+  static function main(args : string[]) : void {
+    new C.<string>("foo").debugLog();
+    new C.<_Main>(new _Main).debugLog();
+    new C.<_Main>(null).debugLog();
+  }
+}
+// vim: set expandtab tabstop=2 shiftwidth=2 ft=jsx: