Add decimal parsing support

packages/babel-core/src/parser/util/missing-plugin-helper.js

@@ -31,6 +31,12 @@ const pluginNameMap = {
       url: "https://git.io/JvpRG",
     },
   },
+  decimal: {
+    syntax: {
+      name: "@babel/plugin-syntax-decimal",
+      url: "https://git.io/JfKOH",
+    },
+  },
   decorators: {
     syntax: {
       name: "@babel/plugin-syntax-decorators",

packages/babel-generator/src/generators/types.js

@@ -222,6 +222,15 @@ export function BigIntLiteral(node: Object) {
   this.token(node.value + "n");
 }
 
+export function DecimalLiteral(node: Object) {
+  const raw = this.getPossibleRaw(node);
+  if (!this.format.minified && raw != null) {
+    this.token(raw);
+    return;
+  }
+  this.token(node.value + "m");
+}
+
 export function PipelineTopicExpression(node: Object) {
   this.print(node.expression, node);
 }

packages/babel-generator/test/fixtures/minified/decimal-literal/input.js

@@ -0,0 +1,5 @@
+100m;
+9223372036854775807m;
+0.m;
+3.1415926535897932m;
+100.000m;

packages/babel-generator/test/fixtures/minified/decimal-literal/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["decimal"],
+  "minified": true
+}

packages/babel-generator/test/fixtures/minified/decimal-literal/output.js

@@ -0,0 +1 @@
+100m;9223372036854775807m;0.m;3.1415926535897932m;100.000m;

packages/babel-generator/test/fixtures/types/DecimalLiteral/input.js

@@ -0,0 +1,5 @@
+100m;
+9223372036854775807m;
+0.m;
+3.1415926535897932m;
+100.000m;

packages/babel-generator/test/fixtures/types/DecimalLiteral/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["decimal"]
+}

packages/babel-generator/test/fixtures/types/DecimalLiteral/output.js

@@ -0,0 +1,5 @@
+100m;
+9223372036854775807m;
+0.m;
+3.1415926535897932m;
+100.000m;

packages/babel-parser/ast/spec.md

@@ -11,6 +11,7 @@ These are the core @babel/parser (babylon) AST node types.
   - [BooleanLiteral](#booleanliteral)
   - [NumericLiteral](#numericliteral)
   - [BigIntLiteral](#bigintliteral)
+  - [DecimalLiteral](#decimalliteral)
 - [Programs](#programs)
 - [Functions](#functions)
 - [Statements](#statements)
@@ -253,6 +254,17 @@ interface BigIntLiteral <: Literal {
 
 The `value` property is the string representation of the `BigInt` value. It doesn't include the suffix `n`.
 
+## DecimalLiteral
+
+```js
+interface DecimalLiteral <: Literal {
+  type: "DecimalLiteral";
+  value: string;
+}
+```
+
+The `value` property is the string representation of the `BigDecimal` value. It doesn't include the suffix `m`.
+
 # Programs
 
 ```js

packages/babel-parser/src/parser/error-message.js

@@ -61,6 +61,7 @@ export const ErrorMessages = Object.freeze({
   ImportOutsideModule: `'import' and 'export' may appear only with 'sourceType: "module"'`,
   InvalidBigIntLiteral: "Invalid BigIntLiteral",
   InvalidCodePoint: "Code point out of bounds",
+  InvalidDecimal: "Invalid decimal",
   InvalidDigit: "Expected number in radix %0",
   InvalidEscapeSequence: "Bad character escape sequence",
   InvalidEscapeSequenceTemplate: "Invalid escape sequence in template",

packages/babel-parser/src/parser/expression.js

@@ -1032,6 +1032,9 @@ export default class ExpressionParser extends LValParser {
       case tt.bigint:
         return this.parseLiteral(this.state.value, "BigIntLiteral");
 
+      case tt.decimal:
+        return this.parseLiteral(this.state.value, "DecimalLiteral");
+
       case tt.string:
         return this.parseLiteral(this.state.value, "StringLiteral");
 
@@ -1859,7 +1862,10 @@ export default class ExpressionParser extends LValParser {
       this.state.inPropertyName = true;
       // We check if it's valid for it to be a private name when we push it.
       (prop: $FlowFixMe).key =
-        this.match(tt.num) || this.match(tt.string) || this.match(tt.bigint)
+        this.match(tt.num) ||
+        this.match(tt.string) ||
+        this.match(tt.bigint) ||
+        this.match(tt.decimal)
           ? this.parseExprAtom()
           : this.parseMaybePrivateName(isPrivateNameAllowed);
 

packages/babel-parser/src/parser/util.js

@@ -273,7 +273,8 @@ export default class UtilParser extends Tokenizer {
       !!this.state.type.keyword ||
       this.match(tt.string) ||
       this.match(tt.num) ||
-      this.match(tt.bigint)
+      this.match(tt.bigint) ||
+      this.match(tt.decimal)
     );
   }
 }

packages/babel-parser/src/plugins/estree.js

@@ -43,6 +43,17 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return node;
     }
 
+    estreeParseDecimalLiteral(value: any): N.Node {
+      // https://github.com/estree/estree/blob/master/experimental/decimal.md
+      // $FlowIgnore
+      // todo: use BigDecimal when node supports it.
+      const decimal = null;
+      const node = this.estreeParseLiteral(decimal);
+      node.decimal = String(node.value || value);
+
+      return node;
+    }
+
     estreeParseLiteral(value: any): N.Node {
       return this.parseLiteral(value, "Literal");
     }
@@ -229,6 +240,9 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         case tt.bigint:
           return this.estreeParseBigIntLiteral(this.state.value);
 
+        case tt.decimal:
+          return this.estreeParseDecimalLiteral(this.state.value);
+
         case tt._null:
           return this.estreeParseLiteral(null);
 

packages/babel-parser/src/tokenizer/index.js

@@ -1095,6 +1095,8 @@ export default class Tokenizer extends ParserErrors {
     if (next === charCodes.lowercaseN) {
       ++this.state.pos;
       isBigInt = true;
+    } else if (next === charCodes.lowercaseM) {
+      throw this.raise(start, Errors.InvalidDecimal);
     }
 
     if (isIdentifierStart(this.input.codePointAt(this.state.pos))) {
@@ -1116,6 +1118,8 @@ export default class Tokenizer extends ParserErrors {
     const start = this.state.pos;
     let isFloat = false;
     let isBigInt = false;
+    let isDecimal = false;
+    let hasExponent = false;
     let isOctal = false;
 
     if (!startsWithDot && this.readInt(10) === null) {
@@ -1157,6 +1161,7 @@ export default class Tokenizer extends ParserErrors {
       }
       if (this.readInt(10) === null) this.raise(start, Errors.InvalidNumber);
       isFloat = true;
+      hasExponent = true;
       next = this.input.charCodeAt(this.state.pos);
     }
 
@@ -1174,18 +1179,32 @@ export default class Tokenizer extends ParserErrors {
       isBigInt = true;
     }
 
+    if (next === charCodes.lowercaseM) {
+      this.expectPlugin("decimal", this.state.pos);
+      if (hasExponent || hasLeadingZero) {
+        this.raise(start, Errors.InvalidDecimal);
+      }
+      ++this.state.pos;
+      isDecimal = true;
+    }
+
     if (isIdentifierStart(this.input.codePointAt(this.state.pos))) {
       throw this.raise(this.state.pos, Errors.NumberIdentifier);
     }
 
-    // remove "_" for numeric literal separator, and "n" for BigInts
-    const str = this.input.slice(start, this.state.pos).replace(/[_n]/g, "");
+    // remove "_" for numeric literal separator, and trailing `m` or `n`
+    const str = this.input.slice(start, this.state.pos).replace(/[_mn]/g, "");
 
     if (isBigInt) {
       this.finishToken(tt.bigint, str);
       return;
     }
 
+    if (isDecimal) {
+      this.finishToken(tt.decimal, str);
+      return;
+    }
+
     const val = isOctal ? parseInt(str, 8) : parseFloat(str);
     this.finishToken(tt.num, val);
   }

packages/babel-parser/src/tokenizer/types.js

@@ -86,6 +86,7 @@ function createBinop(name: string, binop: number) {
 export const types: { [name: string]: TokenType } = {
   num: new TokenType("num", { startsExpr }),
   bigint: new TokenType("bigint", { startsExpr }),
+  decimal: new TokenType("decimal", { startsExpr }),
   regexp: new TokenType("regexp", { startsExpr }),
   string: new TokenType("string", { startsExpr }),
   name: new TokenType("name", { startsExpr }),

packages/babel-parser/test/fixtures/experimental/_no-plugin/decimal/input.js

@@ -0,0 +1 @@
+.1m;

packages/babel-parser/test/fixtures/experimental/_no-plugin/decimal/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "This experimental syntax requires enabling the parser plugin: 'decimal' (1:2)"
+}

packages/babel-parser/test/fixtures/experimental/decimal/decimal-as-property-name/input.js

@@ -0,0 +1 @@
+({ 0m: 0, .1m() {}, get 0.2m(){}, set 3m(_){}, async 4m() {}, *.5m() {} });