bind-gen: Improve newline-handling in code generation

Use of "${ x | trim }" of Mako template unconditionally removes
whitespaces including newlines.  It makes it hard to insert empty
lines in generated code.

This patch revisits the newline problem again, and improves it.

Bug: 839389
Change-Id: If838b4766fe8938e7f7c2bfb2ff8802d56ac9441
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1883830Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709894}

third_party/blink/renderer/bindings/scripts/bind_gen/code_node.py

@@ -264,7 +264,11 @@ class CodeNode(object):
 
     @property
     def renderer(self):
-        return self._renderer or self.outer.renderer
+        # Always use the renderer of the root node in order not to mix renderers
+        # during rendering of a single code node tree.
+        if self.outer is not None:
+            return self.outer.renderer
+        return self._renderer
 
     @property
     def current_render_state(self):
@@ -366,7 +370,7 @@ class SequenceNode(CodeNode):
         template_text = CodeNode.format_template(
             """\
 % for node in {element_nodes}:
-${node | trim}\\
+${node}\\
 % if not loop.last:
 {separator}\\
 % endif
@@ -454,12 +458,16 @@ class SymbolScopeNode(SequenceNode):
     insert corresponding SymbolDefinitionNodes appropriately.
     """
 
-    def __init__(self, code_nodes=None, renderer=None):
+    def __init__(self,
+                 code_nodes=None,
+                 separator="\n",
+                 separator_last="",
+                 renderer=None):
         SequenceNode.__init__(
             self,
             code_nodes=code_nodes,
-            separator="\n",
-            separator_last="\n",
+            separator=separator,
+            separator_last=separator_last,
             renderer=renderer)
 
         self._registered_code_symbols = set()
@@ -703,8 +711,8 @@ class ConditionalExitNode(ConditionalNode):
         template_text = CodeNode.format_template(
             """\
 if (${{{conditional}}}) {{
-  ${{{body} | trim}}
-}}
+  ${{{body}}}
+}}\\
 """, **gensyms)
         template_vars = {
             gensyms["conditional"]: cond,
@@ -803,10 +811,10 @@ class FunctionDefinitionNode(CodeNode):
 
         template_text = CodeNode.format_template(
             """\
-${{{comment} | trim}}
+${{{comment}}}
 ${{{return_type}}} ${{{name}}}(${{{arg_decls}}}) {{
-  ${{{body} | trim}}
-}}
+  ${{{body}}}
+}}\\
 """, **gensyms)
         template_vars = {
             gensyms["name"]: name,

third_party/blink/renderer/bindings/scripts/bind_gen/code_node_test.py

@@ -103,7 +103,7 @@ class CodeNodeTest(unittest.TestCase):
         appropriately.
         """
         renderer = MakoRenderer()
-        root = SymbolScopeNode(renderer=renderer)
+        root = SymbolScopeNode(separator_last="\n", renderer=renderer)
 
         root.register_code_symbols([
             SymbolNode("var1", "int ${var1} = ${var2} + ${var3};"),
@@ -127,7 +127,7 @@ int var1 = var2 + var3;
 
     def test_symbol_definition_with_exit_branches(self):
         renderer = MakoRenderer()
-        root = SymbolScopeNode(renderer=renderer)
+        root = SymbolScopeNode(separator_last="\n", renderer=renderer)
 
         root.register_code_symbols([
             SymbolNode("var1", "int ${var1} = 1;"),
@@ -175,7 +175,7 @@ var3;
 
     def test_symbol_definition_with_nested_exit_branches(self):
         renderer = MakoRenderer()
-        root = SymbolScopeNode(renderer=renderer)
+        root = SymbolScopeNode(separator_last="\n", renderer=renderer)
 
         root.register_code_symbols([
             SymbolNode("var1", "int ${var1} = 1;"),
@@ -229,11 +229,12 @@ if (true) {
 
     def test_function_definition_minimum(self):
         renderer = MakoRenderer()
-        root = FunctionDefinitionNode(
-            name=LiteralNode("blink::bindings::func"),
-            arg_decls=[],
-            return_type=LiteralNode("void"),
-            renderer=renderer)
+        root = SymbolScopeNode(separator_last="\n", renderer=renderer)
+        root.append(
+            FunctionDefinitionNode(
+                name=LiteralNode("blink::bindings::func"),
+                arg_decls=[],
+                return_type=LiteralNode("void")))
 
         self.assertRenderResult(root, """\
 
@@ -244,6 +245,7 @@ void blink::bindings::func() {
 
     def test_function_definition_full(self):
         renderer = MakoRenderer()
+        root = SymbolScopeNode(separator_last="\n", renderer=renderer)
 
         local_vars = [
             SymbolNode("var1", "int ${var1} = 1;"),
@@ -257,18 +259,15 @@ void blink::bindings::func() {
             TextNode("return ${var2};"),
         ])
 
-        root = FunctionDefinitionNode(
-            name=LiteralNode("blink::bindings::func"),
-            arg_decls=[LiteralNode("int arg1"),
-                       LiteralNode("int arg2")],
-            return_type=LiteralNode("void"),
-            local_vars=local_vars,
-            body=func_body,
-            comment=LiteralNode("""\
-// comment1
-// comment2
-"""),
-            renderer=renderer)
+        root.append(
+            FunctionDefinitionNode(
+                name=LiteralNode("blink::bindings::func"),
+                arg_decls=[LiteralNode("int arg1"),
+                           LiteralNode("int arg2")],
+                return_type=LiteralNode("void"),
+                local_vars=local_vars,
+                body=func_body,
+                comment=LiteralNode("// comment1\n// comment2")))
 
         self.assertRenderResult(
             root, """\
@@ -286,8 +285,8 @@ void blink::bindings::func(int arg1, int arg2) {
 
     def test_template_error_handling(self):
         renderer = MakoRenderer()
-
         root = SymbolScopeNode(renderer=renderer)
+
         root.append(
             SymbolScopeNode([
                 # Have Mako raise a NameError.