From 16120bc80e13a557a6065f08c1da24453920241a Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Mon, 3 Jul 2023 11:56:38 +0100
Subject: Parse val statements

---
 .../ast/untyped/UntypedFunctionStatementNode.java  |  2 +-
 .../compiler/ast/untyped/UntypedTargetNode.java    |  7 ++++
 .../compiler/ast/untyped/UntypedValNode.java       | 10 ++++++
 .../java/org/shedlang/compiler/parser/Parser.java  | 38 +++++++++++++++++++++-
 .../shedlang/compiler/typechecker/TypeChecker.java |  3 ++
 5 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/ast/untyped/UntypedTargetNode.java
 create mode 100644 src/main/java/org/shedlang/compiler/ast/untyped/UntypedValNode.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedFunctionStatementNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedFunctionStatementNode.java
index 64704e10..45d71235 100644
--- a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedFunctionStatementNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedFunctionStatementNode.java
@@ -1,4 +1,4 @@
 package org.shedlang.compiler.ast.untyped;
 
-public sealed interface UntypedFunctionStatementNode extends UntypedNode permits UntypedExpressionStatementNode {
+public sealed interface UntypedFunctionStatementNode extends UntypedNode permits UntypedExpressionStatementNode, UntypedValNode {
 }
diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedTargetNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedTargetNode.java
new file mode 100644
index 00000000..514b794a
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedTargetNode.java
@@ -0,0 +1,7 @@
+package org.shedlang.compiler.ast.untyped;
+
+import org.shedlang.compiler.sources.Source;
+
+public sealed interface UntypedTargetNode extends UntypedNode {
+    record Variable(String name, Source source) implements UntypedTargetNode {}
+}
diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedValNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedValNode.java
new file mode 100644
index 00000000..96bbcb42
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedValNode.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.ast.untyped;
+
+import org.shedlang.compiler.sources.Source;
+
+public record UntypedValNode(
+    UntypedTargetNode target,
+    UntypedExpressionNode expression,
+    Source source
+) implements UntypedFunctionStatementNode {
+}
diff --git a/src/main/java/org/shedlang/compiler/parser/Parser.java b/src/main/java/org/shedlang/compiler/parser/Parser.java
index 8b180044..14d9fc6c 100644
--- a/src/main/java/org/shedlang/compiler/parser/Parser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Parser.java
@@ -124,7 +124,13 @@ public class Parser {
     }
 
     static UntypedFunctionStatementNode parseFunctionStatement(TokenIterator<TokenType> tokens) {
-        return parseExpressionStatement(tokens);
+        return switch (tokens.peek().tokenType()) {
+            case KEYWORD_VAL ->
+                parseVal(tokens);
+
+            default ->
+                parseExpressionStatement(tokens);
+        };
     }
 
     private static <T> List<T> parseMany(
@@ -269,4 +275,34 @@ public class Parser {
 
         return new UntypedReferenceNode(name, source);
     }
+
+    private static UntypedTargetNode parseTarget(TokenIterator<TokenType> tokens) {
+        var start = tokens.position();
+
+        var name = tokens.nextValue(TokenType.IDENTIFIER);
+
+        var end = tokens.position();
+        var source = start.to(end);
+
+        return new UntypedTargetNode.Variable(name, source);
+    }
+
+    private static UntypedFunctionStatementNode parseVal(TokenIterator<TokenType> tokens) {
+        var start = tokens.position();
+
+        tokens.skip(TokenType.KEYWORD_VAL);
+
+        var target = parseTarget(tokens);
+
+        tokens.skip(TokenType.SYMBOL_EQUALS);
+
+        var expression = parseTopLevelExpression(tokens);
+
+        tokens.skip(TokenType.SYMBOL_SEMICOLON);
+
+        var end = tokens.position();
+        var source = start.to(end);
+
+        return new UntypedValNode(target, expression, source);
+    }
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 3b128801..c5cb4470 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -259,6 +259,9 @@ public class TypeChecker {
         return switch (untyped) {
             case UntypedExpressionStatementNode expressionStatement ->
                 typeCheckExpressionStatement(expressionStatement, context);
+
+            case UntypedValNode val ->
+                throw new UnsupportedOperationException("TODO");
         };
     }
 
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