Implement precedence in Rust writer

1 files changed, 70 insertions, 27 deletions

diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
index 862d08b..4279f49 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
@@ -403,7 +403,7 @@ public class RustWriterTests {
             .withLengthOperand(RustIntegerLiteral.arbitrary().withValue(47))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("[42; 47]"));
     }
@@ -418,7 +418,7 @@ public class RustWriterTests {
             .withRight(RustPath.of("y"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("x + y"));
     }
@@ -431,7 +431,7 @@ public class RustWriterTests {
             .withRight(RustPath.of("y"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("x == y"));
     }
@@ -444,7 +444,7 @@ public class RustWriterTests {
             .withRight(RustPath.of("y"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("x != y"));
     }
@@ -455,7 +455,7 @@ public class RustWriterTests {
     public void blockExpressionWithNoStatementsAndNoFinalOperand() throws IOException {
         var rust = RustBlockExpression.arbitrary().build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("""
             {
@@ -473,7 +473,7 @@ public class RustWriterTests {
             )
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("""
             {
@@ -488,7 +488,7 @@ public class RustWriterTests {
             .withFinalOperand(RustBoolLiteral.arbitrary().withValue(true))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("""
             {
@@ -508,7 +508,7 @@ public class RustWriterTests {
             .withFinalOperand(RustBoolLiteral.arbitrary().withValue(true))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("""
             {
@@ -524,7 +524,7 @@ public class RustWriterTests {
     public void trueLiteral() throws IOException {
         var rust = RustBoolLiteral.arbitrary().withValue(true).build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("true"));
     }
@@ -533,7 +533,7 @@ public class RustWriterTests {
     public void falseLiteral() throws IOException {
         var rust = RustBoolLiteral.arbitrary().withValue(false).build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("false"));
     }
@@ -546,7 +546,7 @@ public class RustWriterTests {
             .withFunction(RustPath.of("f"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("f()"));
     }
@@ -559,7 +559,7 @@ public class RustWriterTests {
             .addArg(RustPath.of("y"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("f(x, y)"));
     }
@@ -573,7 +573,7 @@ public class RustWriterTests {
             .withFieldName(RustIdentifier.of("y"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("x.y"));
     }
@@ -588,7 +588,7 @@ public class RustWriterTests {
             .withIfFalse(RustBlockExpression.arbitrary().withFinalOperand(RustPath.of("c")))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("""
             if a {
@@ -604,7 +604,7 @@ public class RustWriterTests {
     public void integerLiteralWithoutExplicitType() throws IOException {
         var rust = RustIntegerLiteral.arbitrary().withValue(123).build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("123"));
     }
@@ -616,7 +616,7 @@ public class RustWriterTests {
             .withType(RustIdentifier.of("i32"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("123i32"));
     }
@@ -630,7 +630,7 @@ public class RustWriterTests {
             .withOperand(RustPath.of("x"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("&x"));
     }
@@ -642,7 +642,7 @@ public class RustWriterTests {
             .withOperand(RustPath.of("x"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("&mut x"));
     }
@@ -654,7 +654,7 @@ public class RustWriterTests {
             .withOperand(RustPath.of("x"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("*x"));
     }
@@ -667,7 +667,7 @@ public class RustWriterTests {
             .withStructPath(RustPath.of("A"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("A {}"));
     }
@@ -688,7 +688,7 @@ public class RustWriterTests {
             )
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("X { a: b, c: d }"));
     }
@@ -701,7 +701,7 @@ public class RustWriterTests {
             .withOperand(RustPath.of("a"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("a?"));
     }
@@ -712,7 +712,7 @@ public class RustWriterTests {
     public void tupleExpressionUnit() throws IOException {
         var rust = RustTupleExpression.arbitrary().build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("()"));
     }
@@ -723,7 +723,7 @@ public class RustWriterTests {
             .addElement(RustPath.of("a"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("(a,)"));
     }
@@ -736,11 +736,54 @@ public class RustWriterTests {
             .addElement(RustPath.of("c"))
             .build();
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("(a, b, c)"));
     }
 
+    // === Precedence handling ===
+
+    @Test
+    public void whenSubExpressionHasLowerPrecedenceThenSubExpressionIsParenthesized() throws IOException {
+        var rust = RustBinaryExpression.arbitrary()
+            .withOperator(RustBinaryOperator.ADD)
+            .withLeft(
+                RustBinaryExpression.arbitrary()
+                    .withOperator(RustBinaryOperator.EQUAL)
+                    .withLeft(RustPath.of("x"))
+                    .withRight(RustPath.of("y"))
+            )
+            .withRight(RustPath.of("z"))
+            .build();
+
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
+
+        assertThat(string, equalTo("(x == y) + z"));
+    }
+
+    @Test
+    public void whenSubExpressionsOfLeftAssociativeBinaryOperationHaveSamePrecedenceThenRightExpressionIsParenthesized() throws IOException {
+        var rust = RustBinaryExpression.arbitrary()
+            .withOperator(RustBinaryOperator.ADD)
+            .withLeft(
+                RustBinaryExpression.arbitrary()
+                    .withOperator(RustBinaryOperator.ADD)
+                    .withLeft(RustPath.of("a"))
+                    .withRight(RustPath.of("b"))
+            )
+            .withRight(
+                RustBinaryExpression.arbitrary()
+                    .withOperator(RustBinaryOperator.ADD)
+                    .withLeft(RustPath.of("c"))
+                    .withRight(RustPath.of("d"))
+            )
+            .build();
+
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
+
+        assertThat(string, equalTo("a + b + (c + d)"));
+    }
+
     // == Types ==
 
     @Test
@@ -815,7 +858,7 @@ public class RustWriterTests {
     public void pathSegmentsAreSeparatedByDoubleColons() throws IOException {
         var rust = RustPath.of("std", "string", "String");
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("std::string::String"));
     }
@@ -825,7 +868,7 @@ public class RustWriterTests {
         var rust = RustPath.of("std", "collections", "HashMap")
             .withArgs(List.of(RustPath.of("i32"), RustPath.of("f64")));
 
-        var string = write(writer -> writer.writeExpression(rust));
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
 
         assertThat(string, equalTo("std::collections::HashMap::<i32, f64>"));
     }