Antlr4 - Hierarchical indentation and grouping of binary expressions.

Author: Janther

src/binary-operator-printers/addition.js

@@ -0,0 +1,11 @@
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { bit } from './bit.js';
+import { shift } from './shift.js';
+import { inequality } from './inequality.js';
+import { equality } from './equality.js';
+import { logical } from './logical.js';
+
+export const addition = {
+  match: (op) => ['+', '-'].includes(op),
+  print: binaryOperationPrinter([shift, bit, inequality, equality, logical])
+};

src/binary-operator-printers/arithmetic.js

@@ -1,6 +1,9 @@
-import { arithmetic } from './arithmetic.js';
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { inequality } from './inequality.js';
+import { equality } from './equality.js';
+import { logical } from './logical.js';
 
 export const bit = {
   match: (op) => ['&', '|', '^'].includes(op),
-  print: arithmetic.print
+  print: binaryOperationPrinter([inequality, equality, logical])
 };

src/binary-operator-printers/bit.js

@@ -0,0 +1,7 @@
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { logical } from './logical.js';
+
+export const equality = {
+  match: (op) => ['==', '!='].includes(op),
+  print: binaryOperationPrinter([logical])
+};

src/binary-operator-printers/comparison.js

@@ -1,19 +1,28 @@
 import { doc } from 'prettier';
+import { createBinaryOperationPrinter } from './printers/create-binary-operation-printer.js';
+import { createIndentIfNecessaryBuilder } from './printers/create-indent-if-necessary-builder.js';
+import { multiplication } from './multiplication.js';
+import { addition } from './addition.js';
+import { shift } from './shift.js';
+import { bit } from './bit.js';
+import { inequality } from './inequality.js';
+import { equality } from './equality.js';
+import { logical } from './logical.js';
 
-const { group, indent, line } = doc.builders;
+const { group } = doc.builders;
 
 export const exponentiation = {
   match: (op) => op === '**',
-  print: (node, path, print) => {
-    const right = [' ', node.operator, line, path.call(print, 'right')];
-    // If it's a single binary operation, avoid having a small right
-    // operand like - 1 on its own line
-    const shouldGroup =
-      node.left.type !== 'BinaryOperation' &&
-      path.getParentNode().type !== 'BinaryOperation';
-    return group([
-      path.call(print, 'left'),
-      indent(shouldGroup ? group(right) : right)
-    ]);
-  }
+  print: createBinaryOperationPrinter(
+    () => (document) => group(document), // always group
+    createIndentIfNecessaryBuilder([
+      multiplication,
+      addition,
+      shift,
+      bit,
+      inequality,
+      equality,
+      logical
+    ])
+  )
 };

src/binary-operator-printers/equality.js

@@ -1,7 +1,9 @@
-export * from './arithmetic.js';
+export * from './addition.js';
 export * from './assignment.js';
 export * from './bit.js';
-export * from './comparison.js';
+export * from './equality.js';
 export * from './exponentiation.js';
+export * from './inequality.js';
 export * from './logical.js';
+export * from './multiplication.js';
 export * from './shift.js';

src/binary-operator-printers/exponentiation.js

@@ -0,0 +1,8 @@
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { logical } from './logical.js';
+import { equality } from './equality.js';
+
+export const inequality = {
+  match: (op) => ['<', '>', '<=', '>='].includes(op),
+  print: binaryOperationPrinter([logical, equality])
+};

src/binary-operator-printers/index.js

@@ -1,45 +1,32 @@
 import { doc } from 'prettier';
+import { createBinaryOperationPrinter } from './printers/create-binary-operation-printer.js';
+import { createGroupIfNecessaryBuilder } from './printers/create-group-if-necessary-builder.js';
+import { notIndentParentTypes } from './printers/create-indent-if-necessary-builder.js';
+import { shouldGroupOrIndent } from './utils/should-group-or-indent.js';
 
-const { group, line, indent } = doc.builders;
-
-const groupIfNecessaryBuilder = (path) => (document) =>
-  path.getParentNode().type === 'BinaryOperation' ? document : group(document);
+const { indent } = doc.builders;
 
 const indentIfNecessaryBuilder = (path, options) => (document) => {
   let node = path.getNode();
   for (let i = 0; ; i += 1) {
     const parentNode = path.getParentNode(i);
-    if (parentNode.type === 'ReturnStatement') return document;
-    if (parentNode.type === 'IfStatement') return document;
-    if (parentNode.type === 'WhileStatement') return document;
+    if (notIndentParentTypes.includes(parentNode.type)) return document;
     if (
       options.experimentalTernaries &&
       parentNode.type === 'Conditional' &&
       parentNode.condition === node
     )
       return document;
-    if (parentNode.type !== 'BinaryOperation') return indent(document);
+    if (shouldGroupOrIndent(parentNode, [])) return indent(document);
     if (node === parentNode.right) return document;
     node = parentNode;
   }
 };
 
 export const logical = {
   match: (op) => ['&&', '||'].includes(op),
-  print: (node, path, print, options) => {
-    const groupIfNecessary = groupIfNecessaryBuilder(path);
-    const indentIfNecessary = indentIfNecessaryBuilder(path, options);
-
-    const right = [node.operator, line, path.call(print, 'right')];
-    // If it's a single binary operation, avoid having a small right
-    // operand like - 1 on its own line
-    const shouldGroup =
-      node.left.type !== 'BinaryOperation' &&
-      path.getParentNode().type !== 'BinaryOperation';
-    return groupIfNecessary([
-      path.call(print, 'left'),
-      ' ',
-      indentIfNecessary(shouldGroup ? group(right) : right)
-    ]);
-  }
+  print: createBinaryOperationPrinter(
+    createGroupIfNecessaryBuilder([]),
+    indentIfNecessaryBuilder
+  )
 };

src/binary-operator-printers/inequality.js

@@ -0,0 +1,19 @@
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { addition } from './addition.js';
+import { bit } from './bit.js';
+import { equality } from './equality.js';
+import { inequality } from './inequality.js';
+import { shift } from './shift.js';
+import { logical } from './logical.js';
+
+export const multiplication = {
+  match: (op) => ['*', '/', '%'].includes(op),
+  print: binaryOperationPrinter([
+    addition,
+    shift,
+    bit,
+    inequality,
+    equality,
+    logical
+  ])
+};

src/binary-operator-printers/logical.js

@@ -0,0 +1,9 @@
+import { createBinaryOperationPrinter } from './create-binary-operation-printer.js';
+import { createGroupIfNecessaryBuilder } from './create-group-if-necessary-builder.js';
+import { createIndentIfNecessaryBuilder } from './create-indent-if-necessary-builder.js';
+
+export const binaryOperationPrinter = (shouldGroupAndIndentMatchers) =>
+  createBinaryOperationPrinter(
+    createGroupIfNecessaryBuilder(shouldGroupAndIndentMatchers),
+    createIndentIfNecessaryBuilder(shouldGroupAndIndentMatchers)
+  );

src/binary-operator-printers/multiplication.js

@@ -0,0 +1,28 @@
+import { doc } from 'prettier';
+import { assignment } from '../assignment.js';
+
+const { group, line } = doc.builders;
+
+const rightOperandPrinter = (node, path, print) => {
+  const right = [' ', node.operator, line, path.call(print, 'right')];
+
+  // If it's a single binary operation, avoid having a small right
+  // operand like - 1 on its own line
+  const parent = path.getParentNode();
+  return node.left.type !== 'BinaryOperation' &&
+    parent.type !== 'BinaryOperation'
+    ? group(right)
+    : right;
+};
+
+export const createBinaryOperationPrinter =
+  (groupIfNecessaryBuilder, indentIfNecessaryBuilder) =>
+  (node, path, print, options) => {
+    const groupIfNecessary = groupIfNecessaryBuilder(path);
+    const indentIfNecessary = indentIfNecessaryBuilder(path, options);
+
+    return groupIfNecessary([
+      path.call(print, 'left'),
+      indentIfNecessary(rightOperandPrinter(node, path, print))
+    ]);
+  };

src/binary-operator-printers/printers/binary-operation-printer.js

@@ -0,0 +1,12 @@
+import { doc } from 'prettier';
+import { shouldGroupOrIndent } from '../utils/should-group-or-indent.js';
+
+const { group } = doc.builders;
+
+export const createGroupIfNecessaryBuilder =
+  (shouldIndentMatchers) => (path) => (document) => {
+    const parentNode = path.getParentNode();
+    if (shouldGroupOrIndent(parentNode, shouldIndentMatchers))
+      return group(document);
+    return document;
+  };

src/binary-operator-printers/printers/create-binary-operation-printer.js

@@ -0,0 +1,24 @@
+import { doc } from 'prettier';
+import { shouldGroupOrIndent } from '../utils/should-group-or-indent.js';
+
+const { indent } = doc.builders;
+
+export const notIndentParentTypes = [
+  'ReturnStatement',
+  'IfStatement',
+  'ForStatement',
+  'WhileStatement'
+];
+
+export const createIndentIfNecessaryBuilder =
+  (shouldIndentMatchers) => (path) => (document) => {
+    let node = path.getNode();
+    for (let i = 0; ; i += 1) {
+      const parentNode = path.getParentNode(i);
+      if (notIndentParentTypes.includes(parentNode.type)) return document;
+      if (shouldGroupOrIndent(parentNode, shouldIndentMatchers))
+        return indent(document);
+      if (node === parentNode.right) return document;
+      node = parentNode;
+    }
+  };

src/binary-operator-printers/printers/create-group-if-necessary-builder.js

@@ -1,6 +1,10 @@
-import { arithmetic } from './arithmetic.js';
+import { binaryOperationPrinter } from './printers/binary-operation-printer.js';
+import { bit } from './bit.js';
+import { inequality } from './inequality.js';
+import { equality } from './equality.js';
+import { logical } from './logical.js';
 
 export const shift = {
   match: (op) => ['<<', '>>'].includes(op),
-  print: arithmetic.print
+  print: binaryOperationPrinter([bit, inequality, equality, logical])
 };

src/binary-operator-printers/printers/create-indent-if-necessary-builder.js

@@ -0,0 +1,3 @@
+export const shouldGroupOrIndent = ({ type, operator }, matchers) =>
+  type !== 'BinaryOperation' ||
+  matchers.some((matcher) => matcher.match(operator));