decompiler: Add more decompilable tags

Add more tags to the list of things the decompiler can handle. This
required some changes to track the containing object class in the
DecompileCtx, since some objects use the same tag names.

The improved support means we can test the decompiler on most of the
test suite. Any new test samples will by default be tested to ensure the
decompiler produces the original blueprint file.

Also, updated the decompiler to always use double quotes.

blueprintcompiler/language/expression.py

@@ -18,9 +18,9 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
 
+from ..decompiler import decompile_element
 from .common import *
 from .contexts import ScopeCtx, ValueTypeCtx
-from .gtkbuilder_template import Template
 from .types import TypeName
 
 expr = Sequence()
@@ -274,3 +274,69 @@ expr.children = [
     AnyOf(ClosureExpr, LiteralExpr, ["(", Expression, ")"]),
     ZeroOrMore(AnyOf(LookupOp, CastExpr)),
 ]
+
+
+@decompiler("lookup", skip_children=True, cdata=True)
+def decompile_lookup(
+    ctx: DecompileCtx, gir: gir.GirContext, cdata: str, name: str, type: str
+):
+    if t := ctx.type_by_cname(type):
+        type = decompile.full_name(t)
+    else:
+        type = "$" + type
+
+    assert ctx.current_node is not None
+
+    constant = None
+    if len(ctx.current_node.children) == 0:
+        constant = cdata
+    elif (
+        len(ctx.current_node.children) == 1
+        and ctx.current_node.children[0].tag == "constant"
+    ):
+        constant = ctx.current_node.children[0].cdata
+
+    if constant is not None:
+        if constant == ctx.template_class:
+            ctx.print("template." + name)
+        else:
+            ctx.print(constant + "." + name)
+        return
+    else:
+        for child in ctx.current_node.children:
+            decompile.decompile_element(ctx, gir, child)
+
+    ctx.print(f" as <{type}>.{name}")
+
+
+@decompiler("constant", cdata=True)
+def decompile_constant(
+    ctx: DecompileCtx, gir: gir.GirContext, cdata: str, type: T.Optional[str] = None
+):
+    if type is None:
+        if cdata == ctx.template_class:
+            ctx.print("template")
+        else:
+            ctx.print(cdata)
+    else:
+        ctx.print_value(cdata, ctx.type_by_cname(type))
+
+
+@decompiler("closure", skip_children=True)
+def decompile_closure(ctx: DecompileCtx, gir: gir.GirContext, function: str, type: str):
+    if t := ctx.type_by_cname(type):
+        type = decompile.full_name(t)
+    else:
+        type = "$" + type
+
+    ctx.print(f"${function}(")
+
+    assert ctx.current_node is not None
+    for i, node in enumerate(ctx.current_node.children):
+        decompile_element(ctx, gir, node)
+
+        assert ctx.current_node is not None
+        if i < len(ctx.current_node.children) - 1:
+            ctx.print(", ")
+
+    ctx.end_block_with(f") as <{type}>")