From 11dbdf3ebcac7e254f1c818178f64aa79406f47c Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 1 Oct 2023 21:50:32 +0100
Subject: Add switch instruction to stack IR

---
 .../org/shedlang/compiler/patio/PatioCodeGen.java     |  3 +++
 .../compiler/stackir/InstructionSerializer.java       | 13 +++++++++++++
 .../compiler/stackir/instructions/Instruction.java    |  2 +-
 .../stackir/instructions/SwitchInstruction.java       | 19 +++++++++++++++++++
 4 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/shedlang/compiler/stackir/instructions/SwitchInstruction.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
index 9382eab7..b68bebdf 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
@@ -512,6 +512,9 @@ public class PatioCodeGen {
                     context
                 );
 
+            case SwitchInstruction switch_ ->
+                throw new UnsupportedOperationException("TODO");
+
             case TupleCreateInstruction tupleCreate -> {
                 var elements = new ArrayList<PatioOperand>();
 
diff --git a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
index 6577e2f4..fb2139f5 100644
--- a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
+++ b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
@@ -200,6 +200,19 @@ public class InstructionSerializer {
             case StringAddInstruction stringAddInstruction ->
                 treeList(treeIdentifier("string-add"));
 
+            case SwitchInstruction switchInstruction ->
+                treeListIndented(
+                    treeIdentifier("switch"),
+                    treeListIndented(
+                        switchInstruction.cases().stream()
+                            .map(switchCase -> treeListIndented(
+                                structTypeToTree(switchCase.caseType()),
+                                instructionsToTree(switchCase.body())
+                            ))
+                            .toList()
+                    )
+                );
+
             case TupleCreateInstruction tupleCreateInstruction ->
                 treeList(
                     treeIdentifier("tuple-create"),
diff --git a/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java b/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
index e43acf56..2966e8a7 100644
--- a/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
+++ b/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
@@ -3,7 +3,7 @@ package org.shedlang.compiler.stackir.instructions;
 import org.shedlang.compiler.sources.Source;
 
 public sealed interface Instruction
-    permits CallInstruction, DefineFunctionInstruction, DefineStructInstruction, DiscardInstruction, DuplicateInstruction, FieldLoadInstruction, IfInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, LoopBreakInstruction, LoopContinueInstruction, LoopInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction, StringAddInstruction, TupleCreateInstruction, TupleGetInstruction, VarLoadInstruction, VarStoreInstruction {
+    permits CallInstruction, DefineFunctionInstruction, DefineStructInstruction, DiscardInstruction, DuplicateInstruction, FieldLoadInstruction, IfInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, LoopBreakInstruction, LoopContinueInstruction, LoopInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction, StringAddInstruction, SwitchInstruction, TupleCreateInstruction, TupleGetInstruction, VarLoadInstruction, VarStoreInstruction {
 
     Source source();
 }
diff --git a/src/main/java/org/shedlang/compiler/stackir/instructions/SwitchInstruction.java b/src/main/java/org/shedlang/compiler/stackir/instructions/SwitchInstruction.java
new file mode 100644
index 00000000..85f292e8
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/stackir/instructions/SwitchInstruction.java
@@ -0,0 +1,19 @@
+package org.shedlang.compiler.stackir.instructions;
+
+import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.types.StructType;
+
+import java.util.List;
+
+/**
+ * Pop a value from the stack, find the case corresponding to that value's type,
+ * and execute the instructions in the case's body. If there is no such case,
+ * the behaviour of this instruction is not defined.
+ */
+public record SwitchInstruction(
+    List<Case> cases,
+    Source source
+) implements Instruction {
+    public record Case(StructType caseType, List<Instruction> body, Source source) {
+    }
+}
-- 
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