Add type checking for string literal

7 files changed, 78 insertions, 0 deletions

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedExpressionNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedExpressionNode.java
new file mode 100644
index 00000000..f7ce02dc
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedExpressionNode.java
@@ -0,0 +1,9 @@
+package org.shedlang.compiler.ast.typed;
+
+import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.types.Type;
+
+public sealed interface TypedExpressionNode permits TypedStringLiteralNode {
+    Source source();
+    Type type();
+}
diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedStringLiteralNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedStringLiteralNode.java
new file mode 100644
index 00000000..21f81e2c
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedStringLiteralNode.java
@@ -0,0 +1,15 @@
+package org.shedlang.compiler.ast.typed;
+
+import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.types.Type;
+import org.shedlang.compiler.types.Types;
+
+public record TypedStringLiteralNode(
+    String value,
+    Source source
+) implements TypedExpressionNode {
+    @Override
+    public Type type() {
+        return Types.STRING;
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
new file mode 100644
index 00000000..d37eb347
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -0,0 +1,29 @@
+package org.shedlang.compiler.typechecker;
+
+import org.shedlang.compiler.ast.typed.TypedExpressionNode;
+import org.shedlang.compiler.ast.typed.TypedStringLiteralNode;
+import org.shedlang.compiler.ast.untyped.UntypedCallNode;
+import org.shedlang.compiler.ast.untyped.UntypedExpressionNode;
+import org.shedlang.compiler.ast.untyped.UntypedReferenceNode;
+import org.shedlang.compiler.ast.untyped.UntypedStringLiteralNode;
+
+public class TypeChecker {
+    private TypeChecker() {
+    }
+
+    public static TypedExpressionNode typeCheckExpression(
+        UntypedExpressionNode untyped,
+        TypeCheckerContext context
+    ) {
+        return switch (untyped) {
+            case UntypedStringLiteralNode untypedStringLiteral ->
+                new TypedStringLiteralNode(untypedStringLiteral.value(), untypedStringLiteral.source());
+
+            case UntypedCallNode untypedCall ->
+                throw new UnsupportedOperationException("TODO");
+
+            case UntypedReferenceNode untypedReference ->
+                throw new UnsupportedOperationException("TODO");
+        };
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
new file mode 100644
index 00000000..261e3e95
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
@@ -0,0 +1,5 @@
+package org.shedlang.compiler.typechecker;
+
+public class TypeCheckerContext {
+    public static final TypeCheckerContext EMPTY = new TypeCheckerContext();
+}
diff --git a/src/main/java/org/shedlang/compiler/types/StringType.java b/src/main/java/org/shedlang/compiler/types/StringType.java
new file mode 100644
index 00000000..9b4351cd
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/types/StringType.java
@@ -0,0 +1,8 @@
+package org.shedlang.compiler.types;
+
+public final class StringType implements Type {
+    static final StringType INSTANCE = new StringType();
+
+    private StringType() {
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/types/Type.java b/src/main/java/org/shedlang/compiler/types/Type.java
new file mode 100644
index 00000000..df8cebc5
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/types/Type.java
@@ -0,0 +1,4 @@
+package org.shedlang.compiler.types;
+
+public sealed interface Type permits StringType {
+}
diff --git a/src/main/java/org/shedlang/compiler/types/Types.java b/src/main/java/org/shedlang/compiler/types/Types.java
new file mode 100644
index 00000000..7c3556a5
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/types/Types.java
@@ -0,0 +1,8 @@
+package org.shedlang.compiler.types;
+
+public class Types {
+    private Types() {
+    }
+
+    public static final Type STRING = StringType.INSTANCE;
+}