[Courgette] Refactor: Add and use Instruction*Receptor classes; call ParseFile() in 2 passes.

courgette/adjustment_method_unittest.cc

Index: courgette/adjustment_method_unittest.cc
diff --git a/courgette/adjustment_method_unittest.cc b/courgette/adjustment_method_unittest.cc
index d8b987c2d89e1ac6be8abe036bfa13f72f5ea31b..b560f17692a4d6a0b81cf4ba4fda2db38ee4e811 100644
--- a/courgette/adjustment_method_unittest.cc
+++ b/courgette/adjustment_method_unittest.cc
@@ -49,12 +49,25 @@ class AdjustmentMethodTest : public testing::Test {
     courgette::Label* labelA = prog->FindAbs32Label(kRvaA);
     courgette::Label* labelB = prog->FindAbs32Label(kRvaB);
 
-    EXPECT_TRUE(prog->EmitAbs32(labelA));
-    EXPECT_TRUE(prog->EmitAbs32(labelA));
-    EXPECT_TRUE(prog->EmitAbs32(labelB));
-    EXPECT_TRUE(prog->EmitAbs32(labelA));
-    EXPECT_TRUE(prog->EmitAbs32(labelA));
-    EXPECT_TRUE(prog->EmitAbs32(labelB));
+    auto emit_all = [](courgette::Label* labelA, courgette::Label* labelB,
+                       courgette::InstructionReceptor* receptor) {
+      EXPECT_TRUE(receptor->EmitAbs32(labelA));
+      EXPECT_TRUE(receptor->EmitAbs32(labelA));
+      EXPECT_TRUE(receptor->EmitAbs32(labelB));
+      EXPECT_TRUE(receptor->EmitAbs32(labelA));
+      EXPECT_TRUE(receptor->EmitAbs32(labelA));
+      EXPECT_TRUE(receptor->EmitAbs32(labelB));
+    };
+
+    // Pass 1: Count the space needed to store instructions.
+    courgette::InstructionCountReceptor* count_receptor = nullptr;
+    EXPECT_TRUE(prog->CreateInstructionCountReceptor(&count_receptor));
+    emit_all(labelA, labelB, count_receptor);
+
+    // Pass 2: Emit all instructions.
+    courgette::InstructionStoreReceptor* store_receptor = nullptr;
+    EXPECT_TRUE(prog->CreateInstructionStoreReceptor(&store_receptor));
+    emit_all(labelA, labelB, store_receptor);
 
     if (kind == 0) {
       labelA->index_ = 0;