Parse function expressions

3 files changed, 304 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionExpressionNodeMatcher.java b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionExpressionNodeMatcher.java
new file mode 100644
index 00000000..f5c8d161
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionExpressionNodeMatcher.java
@@ -0,0 +1,54 @@
+package org.shedlang.compiler.ast.untyped;
+
+import org.pcollections.Empty;
+import org.pcollections.PVector;
+import org.shedlang.compiler.testing.MatcherBuilder;
+import org.zwobble.precisely.Matcher;
+
+import java.util.Optional;
+
+import static org.zwobble.precisely.Matchers.has;
+
+public class UntypedFunctionExpressionNodeMatcher extends MatcherBuilder<
+    UntypedExpressionNode,
+    UntypedFunctionExpressionNode,
+    UntypedFunctionExpressionNodeMatcher
+> {
+    public static UntypedFunctionExpressionNodeMatcher empty() {
+        return new UntypedFunctionExpressionNodeMatcher(Empty.vector());
+    }
+
+    public UntypedFunctionExpressionNodeMatcher(
+        PVector<Matcher<? super UntypedFunctionExpressionNode>> submatchers
+    ) {
+        super(submatchers);
+    }
+
+    @Override
+    protected Class<UntypedFunctionExpressionNode> expectedType() {
+        return UntypedFunctionExpressionNode.class;
+    }
+
+    @Override
+    protected UntypedFunctionExpressionNodeMatcher create(
+        PVector<Matcher<? super UntypedFunctionExpressionNode>> submatchers
+    ) {
+        return new UntypedFunctionExpressionNodeMatcher(submatchers);
+    }
+
+    public UntypedFunctionExpressionNodeMatcher withBody(Matcher<UntypedBlockNode> body) {
+        return with(has("body", x -> x.body(), body));
+    }
+
+    public UntypedFunctionExpressionNodeMatcher withEffect(Matcher<Optional<? extends UntypedTypeLevelExpressionNode>> effect) {
+        return with(has("effect", x -> x.effect(), effect));
+    }
+
+    public UntypedFunctionExpressionNodeMatcher withParams(Matcher<UntypedParamsNode> params) {
+        return with(has("params", x -> x.params(), params));
+    }
+
+    public UntypedFunctionExpressionNodeMatcher withReturnType(Matcher<UntypedTypeLevelExpressionNode> returnType) {
+        return with(has("returnType", x -> x.returnType(), returnType));
+    }
+}
diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
index f45adba9..0d4940e8 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
@@ -114,6 +114,10 @@ public class UntypedNodeMatchers {
         return UntypedFunctionDefinitionNodeMatcher.empty();
     }
 
+    public static UntypedFunctionExpressionNodeMatcher isUntypedFunctionExpressionNode() {
+        return UntypedFunctionExpressionNodeMatcher.empty();
+    }
+
     public static Matcher<UntypedFunctionStatementNode> isUntypedFunctionReturnNode(
         Matcher<UntypedExpressionNode> expression
     ) {
diff --git a/src/test/java/org/shedlang/compiler/parser/ParserFunctionExpressionTests.java b/src/test/java/org/shedlang/compiler/parser/ParserFunctionExpressionTests.java
new file mode 100644
index 00000000..d86776be
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/parser/ParserFunctionExpressionTests.java
@@ -0,0 +1,246 @@
+package org.shedlang.compiler.parser;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.parser.errors.PositionalParamAfterNamedParamError;
+import org.shedlang.compiler.tokeniser.UnexpectedTokenException;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.shedlang.compiler.ast.untyped.UntypedNodeMatchers.*;
+import static org.shedlang.compiler.parser.ParserTesting.parseString;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.*;
+
+public class ParserFunctionExpressionTests {
+    @Test
+    public void canParseMinimalFunction() {
+        var source = """
+            fn () -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(isSequence(), isSequence()))
+                .withEffect(isOptionalEmpty())
+                .withReturnType(isUntypedTypeLevelReferenceNode("Unit"))
+                .withBody(isUntypedBlockNode(isSequence()))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithSinglePositionalParam() {
+        var source = """
+            fn (a: Int) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int"))
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithManyPositionalParams() {
+        var source = """
+            fn (a: Int, b: String, c: Bool) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int")),
+                        isUntypedParamNode("b", isUntypedTypeLevelReferenceNode("String")),
+                        isUntypedParamNode("c", isUntypedTypeLevelReferenceNode("Bool"))
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithSingleNamedParam() {
+        var source = """
+            fn (.a: Int) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(),
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int"))
+                    )
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithManyNamedParams() {
+        var source = """
+            fn (.a: Int, .b: String, .c: Bool) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(),
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int")),
+                        isUntypedParamNode("b", isUntypedTypeLevelReferenceNode("String")),
+                        isUntypedParamNode("c", isUntypedTypeLevelReferenceNode("Bool"))
+                    )
+                ))
+        );
+    }
+
+    @Test
+    public void canParseNamedParamAfterPositionalParam() {
+        var source = """
+            fn (a: Int, .b: String) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int"))
+                    ),
+                    isSequence(
+                        isUntypedParamNode("b", isUntypedTypeLevelReferenceNode("String"))
+                    )
+                ))
+        );
+    }
+
+    @Test
+    public void cannotParsePositionalParamAfterNamedParam() {
+        var source = """
+            fn (.a: Int, b: String) -> Unit {
+            }""";
+
+        assertThrows(
+            PositionalParamAfterNamedParamError.class,
+            () -> parseString(source, Parser::parseTopLevelExpression)
+        );
+    }
+
+    @Test
+    public void paramsCanHaveTrailingComma() {
+        var source = """
+            fn (a: Int, ) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int"))
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithEffect() {
+        var source = """
+            fn () ! Io -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withEffect(isOptionalOf(isUntypedTypeLevelReferenceNode("Io")))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithBodyWithoutReturn() {
+        var source = """
+            fn () -> Unit {
+                a;
+                b;
+                c;
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withBody(isUntypedBlockNode(isSequence(
+                    isUntypedExpressionStatementNode(isUntypedReferenceNode("a")),
+                    isUntypedExpressionStatementNode(isUntypedReferenceNode("b")),
+                    isUntypedExpressionStatementNode(isUntypedReferenceNode("c"))
+                )))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithBodyWithBlockReturn() {
+        var source = """
+            fn () -> Unit {
+                a;
+                b;
+                c
+            }""";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionExpressionNode()
+                .withBody(isUntypedBlockNode(isSequence(
+                    isUntypedExpressionStatementNode(isUntypedReferenceNode("a")),
+                    isUntypedExpressionStatementNode(isUntypedReferenceNode("b")),
+                    isUntypedBlockReturnNode(isUntypedReferenceNode("c"))
+                )))
+        );
+    }
+
+    @Test
+    public void blockReturnEndsFunction() {
+        var source = """
+            fn () -> Unit {
+                a;
+                b
+                c
+            }""";
+
+        var error = assertThrows(
+            UnexpectedTokenException.class,
+            () -> parseString(source, Parser::parseTopLevelExpression)
+        );
+
+        assertThat(error.getActual().value(), equalTo("c"));
+        assertThat(error.getExpected(), equalTo(TokenType.SYMBOL_BRACE_CLOSE.toString()));
+    }
+}