From 0b8c4b6a27838e89ff49e1ab66bf2ed4378ec7da Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 14 Jul 2023 21:37:52 +0100
Subject: Compile if expression with single conditional branch

---
 .../org/shedlang/compiler/ast/typed/Typed.java     | 28 +++++++++++++
 .../compiler/stackir/StackCompilerIfTests.java     | 46 ++++++++++++++++++++++
 .../stackir/instructions/InstructionMatchers.java  | 11 ++++++
 3 files changed, 85 insertions(+)
 create mode 100644 src/test/java/org/shedlang/compiler/stackir/StackCompilerIfTests.java

(limited to 'src/test/java')

diff --git a/src/test/java/org/shedlang/compiler/ast/typed/Typed.java b/src/test/java/org/shedlang/compiler/ast/typed/Typed.java
index d52f67a5..160950b6 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/Typed.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/Typed.java
@@ -13,6 +13,10 @@ public class Typed {
     private Typed() {
     }
 
+    public static TypedBlockNode block(List<TypedFunctionStatementNode> statements) {
+        return new TypedBlockNode(statements, Sources.NULL);
+    }
+
     public static TypedBlockReturnNode blockReturn(TypedExpressionNode expression) {
         return new TypedBlockReturnNode(expression, Sources.NULL);
     }
@@ -35,6 +39,17 @@ public class Typed {
         );
     }
 
+    public static TypedConditionalBranchNode conditionalBranch(
+        TypedExpressionNode condition,
+        TypedBlockNode body
+    ) {
+        return new TypedConditionalBranchNode(
+            condition,
+            body,
+            Sources.NULL
+        );
+    }
+
     public static TypedExpressionStatementNode expressionStatement(TypedExpressionNode expression) {
         return new TypedExpressionStatementNode(expression, Sources.NULL);
     }
@@ -43,6 +58,19 @@ public class Typed {
         return new TypedFunctionReturnNode(expression, Sources.NULL);
     }
 
+    public static TypedIfNode if_(
+        List<TypedConditionalBranchNode> conditionalBranches,
+        TypedBlockNode elseBody,
+        Type type
+    ) {
+        return new TypedIfNode(
+            conditionalBranches,
+            elseBody,
+            type,
+            Sources.NULL
+        );
+    }
+
     public static TypedBinaryOperationNode intAdd(
         TypedExpressionNode left,
         TypedExpressionNode right
diff --git a/src/test/java/org/shedlang/compiler/stackir/StackCompilerIfTests.java b/src/test/java/org/shedlang/compiler/stackir/StackCompilerIfTests.java
new file mode 100644
index 00000000..49c47208
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/stackir/StackCompilerIfTests.java
@@ -0,0 +1,46 @@
+package org.shedlang.compiler.stackir;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.typed.Typed;
+import org.shedlang.compiler.types.Types;
+
+import java.util.List;
+
+import static org.shedlang.compiler.stackir.instructions.InstructionMatchers.*;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class StackCompilerIfTests {
+    @Test
+    public void ifWithSingleConditionalBranchIsCompiledToSingleIfInstruction() {
+        var node = Typed.if_(
+            List.of(
+                Typed.conditionalBranch(
+                    Typed.reference("c"),
+                    Typed.block(List.of(
+                        Typed.blockReturn(Typed.intLiteral(42))
+                    ))
+                )
+            ),
+            Typed.block(List.of(
+                Typed.functionReturn(Typed.stringLiteral("x"))
+            )),
+            Types.INT
+        );
+
+        var instructions = StackCompiler.compileExpression(node);
+
+        assertThat(instructions, isSequence(
+            isLocalLoadInstruction("c"),
+            isIfInstruction(
+                isSequence(
+                    isPushIntInstruction(42)
+                ),
+                isSequence(
+                    isPushStringInstruction("x"),
+                    isReturnInstruction()
+                )
+            )
+        ));
+    }
+}
diff --git a/src/test/java/org/shedlang/compiler/stackir/instructions/InstructionMatchers.java b/src/test/java/org/shedlang/compiler/stackir/instructions/InstructionMatchers.java
index 8b2661f7..4be747b7 100644
--- a/src/test/java/org/shedlang/compiler/stackir/instructions/InstructionMatchers.java
+++ b/src/test/java/org/shedlang/compiler/stackir/instructions/InstructionMatchers.java
@@ -33,6 +33,17 @@ public class InstructionMatchers {
         );
     }
 
+    public static Matcher<Instruction> isIfInstruction(
+        Matcher<Iterable<? extends Instruction>> trueBody,
+        Matcher<Iterable<? extends Instruction>> falseBody
+    ) {
+        return instanceOf(
+            IfInstruction.class,
+            has("trueBody", x -> x.trueBody(), trueBody),
+            has("falseBody", x -> x.falseBody(), falseBody)
+        );
+    }
+
     public static Matcher<Instruction> isIntAddInstruction() {
         return instanceOf(IntAddInstruction.class);
     }
-- 
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