generator API: extended definition of 'JoinOptions' used to configure…

… executions of 'joinToNode' * now allows specification of item prefixes and suffixes as fixed values, not only via provider functions * now allows demanding to not append a newline after the last item of given iterable, provided 'appendNewLineIfNotEmpty' is set
eclipse-langium · Oct 9, 2023 · f2a14f9 · f2a14f9
1 parent 4d11fcf
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Showing 2 changed files with 71 additions and 6 deletions.
diff --git a/packages/langium/src/generator/node-joiner.ts b/packages/langium/src/generator/node-joiner.ts
@@ -11,10 +11,11 @@ import { CompositeGeneratorNode, traceToNode } from './generator-node.js';
 
 export interface JoinOptions<T> {
     filter?: (element: T, index: number, isLast: boolean) => boolean;
-    prefix?: (element: T, index: number, isLast: boolean) => Generated | undefined;
-    suffix?: (element: T, index: number, isLast: boolean) => Generated | undefined;
+    prefix?: Generated | ((element: T, index: number, isLast: boolean) => Generated | undefined);
+    suffix?: Generated | ((element: T, index: number, isLast: boolean) => Generated | undefined);
     separator?: Generated;
     appendNewLineIfNotEmpty?: true;
+    skipNewLineAfterLastItem?: true;
 }
 
 const defaultToGenerated = (e: unknown): Generated => e === undefined || typeof e === 'string' || isGeneratorNode(e) ? e : String(e);
@@ -100,23 +101,28 @@ export function joinToNode<T>(
 ): CompositeGeneratorNode | undefined {
 
     const toGenerated = typeof toGeneratedOrOptions === 'function' ? toGeneratedOrOptions : defaultToGenerated;
-    const { filter, prefix, suffix, separator, appendNewLineIfNotEmpty } = typeof toGeneratedOrOptions === 'object' ? toGeneratedOrOptions : options;
+    const { filter, prefix, suffix, separator, appendNewLineIfNotEmpty, skipNewLineAfterLastItem } = typeof toGeneratedOrOptions === 'object' ? toGeneratedOrOptions : options;
+
+    const prefixFunc = typeof prefix === 'function' ? prefix : undefined;
+    const suffixFunc = typeof suffix === 'function' ? suffix : undefined;
 
     return reduceWithIsLast(iterable, (node, it, i, isLast) => {
         if (filter && !filter(it, i, isLast)) {
             return node;
         }
         const content = toGenerated(it, i, isLast);
         return (node ??= new CompositeGeneratorNode())
-            .append(prefix && prefix(it, i, isLast))
+            .append(prefixFunc && prefixFunc(it, i, isLast) || prefix as Generated)
             .append(content)
-            .append(suffix && suffix(it, i, isLast))
+            .append(suffixFunc && suffixFunc(it, i, isLast) || suffix as Generated)
             .appendIf(!isLast && content !== undefined, separator)
             .appendNewLineIfNotEmptyIf(
                 // append 'newLineIfNotEmpty' elements only if 'node' has some content already,
                 //  as if the parent is an IndentNode with 'indentImmediately' set to 'false'
                 //  the indentation is not properly applied to the first non-empty line of the (this) child node
-                !node.isEmpty() && !!appendNewLineIfNotEmpty
+                // besides, append the newLine only if more lines are following, if appending a newline
+                //  is not suppressed for the final item
+                !node.isEmpty() && !!appendNewLineIfNotEmpty && (!isLast || !skipNewLineAfterLastItem)
             );
     });
 }

diff --git a/packages/langium/test/generator/template-node.test.ts b/packages/langium/test/generator/template-node.test.ts
@@ -951,6 +951,17 @@ describe('Embedded forEach loops', () => {
         `);
     });
     test('ForEach loop with element prefix and Array input', () => {
+        const node = n`
+            Data:
+              ${joinToNode(['a', 'b'], String, { prefix: ',' })}
+        `;
+        const text = toString(node);
+        expect(text).toBe(s`
+            Data:
+              ,a,b
+        `);
+    });
+    test('ForEach loop with element prefix and Array input 2 (function)', () => {
         const node = n`
             Data:
               ${joinToNode(['a', 'b'], String, { prefix: (e, i) => i === 0 ? '': ', ' })}
@@ -962,6 +973,17 @@ describe('Embedded forEach loops', () => {
         `);
     });
     test('ForEach loop with element suffix and Set input', () => {
+        const node = n`
+            Data:
+              ${joinToNode(new Set(['a', 'b']), String, { suffix: ',' })}
+        `;
+        const text = toString(node);
+        expect(text).toBe(s`
+            Data:
+              a,b,
+        `);
+    });
+    test('ForEach loop with element suffix and Set input 2 (function)', () => {
         const node = n`
             Data:
               ${joinToNode(new Set(['a', 'b']), String, { suffix: (e, i, isLast) => isLast ? '': ', ' })}
@@ -996,6 +1018,18 @@ describe('Embedded forEach loops', () => {
             
         `);
     });
+    test('ForEach loop with line breaks and skip line break after last line and Stream input', () => {
+        const node = n`
+            Data:
+              ${joinToNode(stream(['a', 'b']), String, { appendNewLineIfNotEmpty: true, skipNewLineAfterLastItem: true})}
+        `;
+        const text = toString(node);
+        expect(text).toBe(s`
+            Data:
+              a
+              b
+        `);
+    });
     test('ForEach loop with separator, line breaks, and Stream input', () => {
         const node = n`
             Data:
@@ -1010,6 +1044,19 @@ describe('Embedded forEach loops', () => {
             
         `);
     });
+    test('ForEach loop with separator, line breaks and skip line break after last line, and Stream input', () => {
+        const node = n`
+            Data:
+              ${joinToNode(stream(['a', undefined, 'b']), String, { separator: ',', appendNewLineIfNotEmpty: true, skipNewLineAfterLastItem: true})}
+        `;
+        const text = toString(node);
+        expect(text).toBe(s`
+            Data:
+              a,
+              undefined,
+              b
+        `);
+    });
     test('ForEach loop with omitted `undefined`, separator, line breaks and Stream input', () => {
         const node = n`
             Data:
@@ -1023,6 +1070,18 @@ describe('Embedded forEach loops', () => {
             
         `);
     });
+    test('ForEach loop with omitted `undefined`, separator, line breaks and skip line break after last line, and Stream input', () => {
+        const node = n`
+            Data:
+              ${joinToNode(stream(['a', undefined, 'b']), e => e && String(e), { separator: ',', appendNewLineIfNotEmpty: true, skipNewLineAfterLastItem: true})}
+        `;
+        const text = toString(node);
+        expect(text).toBe(s`
+            Data:
+              a,
+              b
+        `);
+    });
 });
 
 describe('Appending templates to existing nodes', () => {