From 511304a1a553249a2d26f8b6ac227190641ec614 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 21 Jul 2023 12:38:04 +0100
Subject: Add function declarations to Patio

---
 .../patio/ast/PatioCompilationUnitElement.java     |  2 +-
 .../patio/ast/PatioFunctionDeclaration.java        | 64 ++++++++++++++++++++++
 .../compiler/patio/ast/PatioSerializer.java        | 12 ++++
 3 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/shedlang/compiler/patio/ast/PatioFunctionDeclaration.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/patio/ast/PatioCompilationUnitElement.java b/src/main/java/org/shedlang/compiler/patio/ast/PatioCompilationUnitElement.java
index d4ad4715..61cccb91 100644
--- a/src/main/java/org/shedlang/compiler/patio/ast/PatioCompilationUnitElement.java
+++ b/src/main/java/org/shedlang/compiler/patio/ast/PatioCompilationUnitElement.java
@@ -2,7 +2,7 @@ package org.shedlang.compiler.patio.ast;
 
 import org.shedlang.compiler.sources.Source;
 
-public sealed interface PatioCompilationUnitElement permits PatioDataElement, PatioFunctionDefinition {
+public sealed interface PatioCompilationUnitElement permits PatioDataElement, PatioFunctionDeclaration, PatioFunctionDefinition {
     String name();
     Source source();
 }
diff --git a/src/main/java/org/shedlang/compiler/patio/ast/PatioFunctionDeclaration.java b/src/main/java/org/shedlang/compiler/patio/ast/PatioFunctionDeclaration.java
new file mode 100644
index 00000000..28810b5e
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/patio/ast/PatioFunctionDeclaration.java
@@ -0,0 +1,64 @@
+package org.shedlang.compiler.patio.ast;
+
+import org.pcollections.PVector;
+import org.shedlang.compiler.patio.ast.types.PatioType;
+import org.shedlang.compiler.patio.ast.types.PatioTypes;
+import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.sources.Sources;
+import org.shedlang.compiler.util.P;
+
+import java.util.List;
+
+public record PatioFunctionDeclaration(
+    String name,
+    List<PatioLocal> params,
+    PatioType returnType,
+    Source source
+) implements PatioCompilationUnitElement {
+    public static Builder builder() {
+        return new Builder(
+            "f",
+            P.vector(),
+            PatioTypes.INT
+        );
+    }
+
+    public record Builder(
+        String name,
+        PVector<PatioLocal> params,
+        PatioType returnType
+    ) {
+        public Builder withName(String name) {
+            return new Builder(
+                name,
+                this.params,
+                this.returnType
+            );
+        }
+
+        public Builder addParam(PatioLocal param) {
+            return new Builder(
+                this.name,
+                this.params.plus(param),
+                this.returnType
+            );
+        }
+
+        public Builder withReturnType(PatioType returnType) {
+            return new Builder(
+                this.name,
+                this.params,
+                returnType
+            );
+        }
+
+        public PatioFunctionDeclaration build() {
+            return new PatioFunctionDeclaration(
+                this.name,
+                this.params,
+                this.returnType,
+                Sources.NULL
+            );
+        }
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/patio/ast/PatioSerializer.java b/src/main/java/org/shedlang/compiler/patio/ast/PatioSerializer.java
index 25552eb2..e5245d0a 100644
--- a/src/main/java/org/shedlang/compiler/patio/ast/PatioSerializer.java
+++ b/src/main/java/org/shedlang/compiler/patio/ast/PatioSerializer.java
@@ -80,6 +80,18 @@ public class PatioSerializer {
                     dataLayoutToTree(dataElement.layout())
                 );
 
+            case PatioFunctionDeclaration functionDeclaration ->
+                treeListIndented(
+                    treeIdentifier("function-decl"),
+                    treeString(element.name()),
+                    treeNamed("params", treeList(
+                        functionDeclaration.params().stream()
+                            .map(param -> localToTree(param))
+                            .toList()
+                    )),
+                    treeNamed("return-type", typeToTree(functionDeclaration.returnType()))
+                );
+
             case PatioFunctionDefinition functionDefinition ->
                 treeListIndented(
                     treeIdentifier("function"),
-- 
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