fix: improve throws formatting

Author: jtkiesel

packages/prettier-plugin-java/src/printers/classes.ts

@@ -12,7 +12,14 @@ import {
   sortClassTypeChildren,
   sortModifiers
 } from "./printer-utils";
-import { concat, group, indent, join, indentIfBreak } from "./prettier-builder";
+import {
+  concat,
+  group,
+  ifBreak,
+  indent,
+  join,
+  indentIfBreak
+} from "./prettier-builder";
 import { printTokenWithComments } from "./comments/format-comments";
 import {
   hasLeadingComments,
@@ -509,18 +516,23 @@ export class ClassesPrettierVisitor extends BaseCstPrettierPrinter {
 
   methodDeclaration(ctx: MethodDeclarationCtx) {
     const modifiers = sortModifiers(ctx.methodModifier);
+    const throwsGroupId = Symbol("throws");
     const firstAnnotations = this.mapVisit(modifiers[0]);
     const otherModifiers = this.mapVisit(modifiers[1]);
 
-    const header = this.visit(ctx.methodHeader);
+    const header = this.visit(ctx.methodHeader, { throwsGroupId });
     const body = this.visit(ctx.methodBody);
 
-    const headerBodySeparator = isStatementEmptyStatement(body) ? "" : " ";
+    const headerBodySeparator = isStatementEmptyStatement(body)
+      ? ""
+      : ctx.methodHeader[0].children.throws
+      ? ifBreak(hardline, " ", { groupId: throwsGroupId })
+      : " ";
 
     return rejectAndJoin(hardline, [
-      rejectAndJoin(hardline, firstAnnotations),
+      ...firstAnnotations,
       rejectAndJoin(" ", [
-        rejectAndJoin(" ", otherModifiers),
+        ...otherModifiers,
         rejectAndJoin(headerBodySeparator, [header, body])
       ])
     ]);
@@ -534,12 +546,12 @@ export class ClassesPrettierVisitor extends BaseCstPrettierPrinter {
     return printTokenWithComments(this.getSingle(ctx) as IToken);
   }
 
-  methodHeader(ctx: MethodHeaderCtx) {
+  methodHeader(ctx: MethodHeaderCtx, opts?: { throwsGroupId?: symbol }) {
     const typeParameters = this.visit(ctx.typeParameters);
     const annotations = this.mapVisit(ctx.annotation);
     const result = this.visit(ctx.result);
     const declarator = this.visit(ctx.methodDeclarator);
-    const throws = this.visit(ctx.throws);
+    const throws = this.visit(ctx.throws, opts);
 
     return group(
       concat([
@@ -646,15 +658,16 @@ export class ClassesPrettierVisitor extends BaseCstPrettierPrinter {
     return printTokenWithComments(this.getSingle(ctx) as IToken);
   }
 
-  throws(ctx: ThrowsCtx) {
+  throws(ctx: ThrowsCtx, opts?: { throwsGroupId?: symbol }) {
     const exceptionTypeList = this.visit(ctx.exceptionTypeList);
-    const throwsDeclaration = join(" ", [ctx.Throws[0], exceptionTypeList]);
-    return group(indent(rejectAndConcat([softline, throwsDeclaration])));
+    return group(indent(join(line, [ctx.Throws[0], exceptionTypeList])), {
+      id: opts?.throwsGroupId
+    });
   }
 
   exceptionTypeList(ctx: ExceptionTypeListCtx) {
     const exceptionTypes = this.mapVisit(ctx.exceptionType);
-    const commas = ctx.Comma ? ctx.Comma.map(elt => concat([elt, " "])) : [];
+    const commas = ctx.Comma?.map(comma => concat([comma, line]));
     return rejectAndJoinSeps(commas, exceptionTypes);
   }
 
@@ -681,25 +694,26 @@ export class ClassesPrettierVisitor extends BaseCstPrettierPrinter {
   }
 
   constructorDeclaration(ctx: ConstructorDeclarationCtx) {
+    const throwsGroupId = Symbol("throws");
     const modifiers = sortModifiers(ctx.constructorModifier);
     const firstAnnotations = this.mapVisit(modifiers[0]);
     const otherModifiers = this.mapVisit(modifiers[1]);
-
     const constructorDeclarator = this.visit(ctx.constructorDeclarator);
-    const throws = this.visit(ctx.throws);
+    const throws = this.visit(ctx.throws, { throwsGroupId });
     const constructorBody = this.visit(ctx.constructorBody);
 
-    return rejectAndJoin(" ", [
+    return concat([
       group(
         rejectAndJoin(hardline, [
           rejectAndJoin(hardline, firstAnnotations),
           rejectAndJoin(" ", [
-            join(" ", otherModifiers),
+            rejectAndJoin(" ", otherModifiers),
             constructorDeclarator,
             throws
           ])
         ])
       ),
+      ctx.throws ? ifBreak(hardline, " ", { groupId: throwsGroupId }) : " ",
       constructorBody
     ]);
   }

packages/prettier-plugin-java/src/printers/prettier-builder.ts

@@ -53,11 +53,13 @@ export function dedent(doc: Doc | IToken) {
 
 export function ifBreak(
   breakContents: Doc | IToken,
-  flatContents: Doc | IToken
+  flatContents: Doc | IToken,
+  options?: { groupId?: symbol | undefined }
 ) {
   return builders.ifBreak(
     processComments(breakContents),
-    processComments(flatContents)
+    processComments(flatContents),
+    options
   );
 }
 

packages/prettier-plugin-java/test/unit-test/throws/_output.java

@@ -8,23 +8,33 @@ void throwException2(String string) throws RuntimeException {
     throw new RuntimeException();
   }
 
-  void throwException3(String string1, String string2, String string3)
-    throws RuntimeException {
+  void throwException3(String string1, String string2, String string3) throws
+    RuntimeException
+  {
     throw new RuntimeException();
   }
 
-  void throwException4()
-    throws RuntimeException, RuntimeException, RuntimeException {
+  void throwException4() throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException
+  {
     throw new RuntimeException();
   }
 
-  void throwException5(String string)
-    throws RuntimeException, RuntimeException, RuntimeException {
+  void throwException5(String string) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException
+  {
     throw new RuntimeException();
   }
 
-  void throwException6(String string1, String string2, String string3)
-    throws RuntimeException, RuntimeException, RuntimeException {
+  void throwException6(String string1, String string2, String string3) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException
+  {
     throw new RuntimeException();
   }
 
@@ -51,19 +61,33 @@ void throwException9(
     String string2,
     String string3,
     String string4
-  )
-    throws RuntimeException, RuntimeException, RuntimeException, RuntimeException {
+  ) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException,
+    RuntimeException
+  {
     throw new RuntimeException();
   }
 
-  void aVeryLongNameForAMethodWichShouldBreakTheExpression()
-    throws aVeryLongException {}
-
-  void aVeryLongNameForAMethodWichShouldBreakTheExpression()
-    throws aVeryLongException, aVeryLongException {}
-
-  void aVeryLongNameForAMethodWichShouldBreakTheExpression()
-    throws Exception, Exception, Exception, Exception, Exception, Exception, Exception {}
+  void aVeryLongNameForAMethodWichShouldBreakTheExpression() throws
+    aVeryLongException
+  {}
+
+  void aVeryLongNameForAMethodWichShouldBreakTheExpression() throws
+    aVeryLongException,
+    aVeryLongException
+  {}
+
+  void aVeryLongNameForAMethodWichShouldBreakTheExpression() throws
+    Exception,
+    Exception,
+    Exception,
+    Exception,
+    Exception,
+    Exception,
+    Exception
+  {}
 
   abstract void absThrowException1() throws RuntimeException;
 
@@ -75,11 +99,15 @@ abstract void absThrowException3(
     String string3
   ) throws RuntimeException;
 
-  abstract void absThrowException4()
-    throws RuntimeException, RuntimeException, RuntimeException;
+  abstract void absThrowException4() throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException;
 
-  abstract void absThrowException5(String string)
-    throws RuntimeException, RuntimeException, RuntimeException;
+  abstract void absThrowException5(String string) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException;
 
   abstract void absThrowException6(
     String string1,
@@ -99,15 +127,19 @@ abstract void absThrowException8(
     String string2,
     String string3,
     String string4
-  )
-    throws RuntimeException, RuntimeException, RuntimeException, RuntimeException;
+  ) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException,
+    RuntimeException;
 
   public Throws(String string1) throws RuntimeException {
     System.out.println("Constructor with throws that should not wrap");
   }
 
-  public Throws(String string1, String string2, String string3)
-    throws RuntimeException {
+  public Throws(String string1, String string2, String string3) throws
+    RuntimeException
+  {
     System.out.println("Constructor with throws that should wrap");
   }
 
@@ -127,8 +159,12 @@ public Throws(
     String string3,
     String string4,
     String string5
-  )
-    throws RuntimeException, RuntimeException, RuntimeException, RuntimeException {
+  ) throws
+    RuntimeException,
+    RuntimeException,
+    RuntimeException,
+    RuntimeException
+  {
     System.out.println("Constructor with throws that should wrap");
   }
 }