fix(python) Fix recognition of numeric literals followed by keywords …

…without whitespace

Fixes highlightjs#2985

src/languages/python.js

@@ -255,6 +255,12 @@ export default function(hljs) {
   // https://docs.python.org/3.9/reference/lexical_analysis.html#numeric-literals
   const digitpart = '[0-9](_?[0-9])*';
   const pointfloat = `(\\b(${digitpart}))?\\.(${digitpart})|\\b(${digitpart})\\.`;
+  // Whitespace after a number (or any lexical token) is needed only if its absence
+  // would change the tokenization
+  // https://docs.python.org/3.9/reference/lexical_analysis.html#whitespace-between-tokens
+  // We deviate slightly, requiring a word boundary or a keyword
+  // to avoid accidentally recognizing *prefixes* (e.g., `0` in `0x41` or `08` or `0__1`)
+  const lookahead = `\\b|${RESERVED_WORDS.join('|')}`;
   const NUMBER = {
     className: 'number',
     relevance: 0,
@@ -270,7 +276,7 @@ export default function(hljs) {
       // because both MUST contain a decimal point and so cannot be confused with
       // the interior part of an identifier
       {
-        begin: `(\\b(${digitpart})|(${pointfloat}))[eE][+-]?(${digitpart})[jJ]?\\b`
+        begin: `(\\b(${digitpart})|(${pointfloat}))[eE][+-]?(${digitpart})[jJ]?(?=${lookahead})`
       },
       {
         begin: `(${pointfloat})[jJ]?`
@@ -283,22 +289,22 @@ export default function(hljs) {
       // decinteger is optionally imaginary
       // https://docs.python.org/3.9/reference/lexical_analysis.html#imaginary-literals
       {
-        begin: '\\b([1-9](_?[0-9])*|0+(_?0)*)[lLjJ]?\\b'
+        begin: `\\b([1-9](_?[0-9])*|0+(_?0)*)[lLjJ]?(?=${lookahead})`
       },
       {
-        begin: '\\b0[bB](_?[01])+[lL]?\\b'
+        begin: `\\b0[bB](_?[01])+[lL]?(?=${lookahead})`
       },
       {
-        begin: '\\b0[oO](_?[0-7])+[lL]?\\b'
+        begin: `\\b0[oO](_?[0-7])+[lL]?(?=${lookahead})`
       },
       {
-        begin: '\\b0[xX](_?[0-9a-fA-F])+[lL]?\\b'
+        begin: `\\b0[xX](_?[0-9a-fA-F])+[lL]?(?=${lookahead})`
       },
 
       // imagnumber (digitpart-based)
       // https://docs.python.org/3.9/reference/lexical_analysis.html#imaginary-literals
       {
-        begin: `\\b(${digitpart})[jJ]\\b`
+        begin: `\\b(${digitpart})[jJ](?=${lookahead})`
       }
     ]
   };