Parse if expressions

2 files changed, 124 insertions, 0 deletions

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 bc237a00..17675e35 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
@@ -38,6 +38,17 @@ public class UntypedNodeMatchers {
         return UntypedCallNodeMatcher.empty();
     }
 
+    public static Matcher<UntypedConditionalBranchNode> isUntypedConditionalBranchNode(
+        Matcher<UntypedExpressionNode> condition,
+        Matcher<Iterable<? extends UntypedFunctionStatementNode>> body
+    ) {
+        return instanceOf(
+            UntypedConditionalBranchNode.class,
+            has("condition", x -> x.condition(), condition),
+            has("body", x -> x.body(), body)
+        );
+    }
+
     public static Matcher<UntypedExpressionNode> isUntypedEqualsNode(
         Matcher<UntypedExpressionNode> left,
         Matcher<UntypedExpressionNode> right
@@ -58,6 +69,17 @@ public class UntypedNodeMatchers {
         return UntypedFunctionDefinitionNodeMatcher.empty();
     }
 
+    public static Matcher<UntypedExpressionNode> isUntypedIfNode(
+        Matcher<Iterable<? extends UntypedConditionalBranchNode>> conditionalBranches,
+        Matcher<Iterable<? extends UntypedFunctionStatementNode>> elseBody
+    ) {
+        return instanceOf(
+            UntypedIfNode.class,
+            has("conditionalBranches", x -> x.conditionalBranches(), conditionalBranches),
+            has("elseBody", x -> x.elseBody(), elseBody)
+        );
+    }
+
     public static Matcher<UntypedExpressionNode> isUntypedIntLiteralNode(int value) {
         return isUntypedIntLiteralNode(BigInteger.valueOf(value));
     }
diff --git a/src/test/java/org/shedlang/compiler/parser/ParserIfTests.java b/src/test/java/org/shedlang/compiler/parser/ParserIfTests.java
new file mode 100644
index 00000000..5de0988d
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/parser/ParserIfTests.java
@@ -0,0 +1,102 @@
+package org.shedlang.compiler.parser;
+
+import org.junit.jupiter.api.Test;
+
+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.isSequence;
+
+public class ParserIfTests {
+    @Test
+    public void canParseIfWithSingleConditionalBranchAndNoElse() {
+        var source = "if (a) { 1; }";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(node, isUntypedIfNode(
+            isSequence(
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("a"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(1))
+                    )
+                )
+            ),
+            isSequence()
+        ));
+    }
+
+    @Test
+    public void canParseIfWithSingleConditionalBranchAndElse() {
+        var source = "if (a) { 1; } else { 2; }";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(node, isUntypedIfNode(
+            isSequence(
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("a"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(1))
+                    )
+                )
+            ),
+            isSequence(
+                isUntypedExpressionStatementNode(isUntypedIntLiteralNode(2))
+            )
+        ));
+    }
+
+    @Test
+    public void canParseIfWithManyConditionalBranchesAndNoElse() {
+        var source = "if (a) { 1; } else if (b) { 2; }";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(node, isUntypedIfNode(
+            isSequence(
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("a"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(1))
+                    )
+                ),
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("b"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(2))
+                    )
+                )
+            ),
+            isSequence()
+        ));
+    }
+
+    @Test
+    public void canParseIfWithManyConditionalBranchesAndElse() {
+        var source = "if (a) { 1; } else if (b) { 2; } else { 3; }";
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(node, isUntypedIfNode(
+            isSequence(
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("a"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(1))
+                    )
+                ),
+                isUntypedConditionalBranchNode(
+                    isUntypedReferenceNode("b"),
+                    isSequence(
+                        isUntypedExpressionStatementNode(isUntypedIntLiteralNode(2))
+                    )
+                )
+            ),
+            isSequence(
+                isUntypedExpressionStatementNode(isUntypedIntLiteralNode(3))
+            )
+        ));
+    }
+}