Parse function types

1 files changed, 168 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/parser/ParserFunctionTypeTests.java b/src/test/java/org/shedlang/compiler/parser/ParserFunctionTypeTests.java
new file mode 100644
index 00000000..467930a3
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/parser/ParserFunctionTypeTests.java
@@ -0,0 +1,168 @@
+package org.shedlang.compiler.parser;
+
+import org.junit.jupiter.api.Test;
+
+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 ParserFunctionTypeTests {
+    @Test
+    public void canParseFunctionTypeWithNoParamsAndNoEffect() {
+        var source = "fn () -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    isSequence(),
+                    isSequence()
+                ))
+                .withEffect(isOptionalEmpty())
+                .withReturnType(isUntypedTypeLevelReferenceNode("Unit"))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithSinglePositionalParam() {
+        var source = "fn (Int) -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    isSequence(
+                        isUntypedTypeLevelReferenceNode("Int")
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithManyPositionalParams() {
+        var source = "fn (Int, String, Bool) -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    isSequence(
+                        isUntypedTypeLevelReferenceNode("Int"),
+                        isUntypedTypeLevelReferenceNode("String"),
+                        isUntypedTypeLevelReferenceNode("Bool")
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionWithSingleNamedParam() {
+        var source = "fn (.a: Int) -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    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::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    isSequence(),
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int")),
+                        isUntypedParamNode("b", isUntypedTypeLevelReferenceNode("String")),
+                        isUntypedParamNode("c", isUntypedTypeLevelReferenceNode("Bool"))
+                    )
+                ))
+        );
+    }
+
+    @Test
+    public void canParseNamedParamAfterPositionalParam() {
+        var source = "fn (Int, .b: String) -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withParams(isUntypedParamTypesNode(
+                    isSequence(
+                        isUntypedTypeLevelReferenceNode("Int")
+                    ),
+                    isSequence(
+                        isUntypedParamNode("b", isUntypedTypeLevelReferenceNode("String"))
+                    )
+                ))
+        );
+    }
+
+    @Test
+    public void cannotParsePositionalParamAfterNamedParam() {
+        var source = "fn (.a: Int, String) -> Unit";
+
+        assertThrows(
+            PositionalParamAfterNamedParamError.class,
+            () -> parseString(source, Parser::parseTopLevelTypeLevelExpression)
+        );
+    }
+
+    @Test
+    public void paramsCanHaveTrailingComma() {
+        var source = """
+            fun f(a: Int, ) -> Unit {
+            }""";
+
+        var node = parseString(source, Parser::parseNamespaceStatement);
+
+        assertThat(
+            node,
+            isUntypedFunctionDefinitionNode()
+                .withParams(isUntypedParamsNode(
+                    isSequence(
+                        isUntypedParamNode("a", isUntypedTypeLevelReferenceNode("Int"))
+                    ),
+                    isSequence()
+                ))
+        );
+    }
+
+    @Test
+    public void canParseFunctionTypeWithEffect() {
+        var source = "fn () ! Io -> Unit";
+
+        var node = parseString(source, Parser::parseTopLevelTypeLevelExpression);
+
+        assertThat(
+            node,
+            isUntypedFunctionTypeNode()
+                .withEffect(isOptionalOf(isUntypedTypeLevelReferenceNode("Io")))
+        );
+    }
+}