Issue 5164: Allow capital E in scientific notation (#5242)

* Remove prohibition of capital E exponent signifier

* Remove exponent error format test

* Add test for lowercase 'e' in exponent notation

* Update output

Co-authored-by: Geoffrey Booth <webadmin@geoffreybooth.com>

Author: rdeforest

docs/v2/annotated-source/lexer.html

@@ -552,9 +552,6 @@ <h2 id="tokenizers">Tokenizers</h2>
     <span class="hljs-keyword">switch</span>
       <span class="hljs-keyword">when</span> <span class="hljs-regexp">/^0[BOX]/</span>.test number
         @error <span class="hljs-string">&quot;radix prefix in &#x27;<span class="hljs-subst">#{number}</span>&#x27; must be lowercase&quot;</span>, offset: <span class="hljs-number">1</span>
-      <span class="hljs-keyword">when</span> <span class="hljs-regexp">/^(?!0x).*E/</span>.test number
-        @error <span class="hljs-string">&quot;exponential notation in &#x27;<span class="hljs-subst">#{number}</span>&#x27; must be indicated with a lowercase &#x27;e&#x27;&quot;</span>,
-          offset: number.indexOf(<span class="hljs-string">&#x27;E&#x27;</span>)
       <span class="hljs-keyword">when</span> <span class="hljs-regexp">/^0\d*[89]/</span>.test number
         @error <span class="hljs-string">&quot;decimal literal &#x27;<span class="hljs-subst">#{number}</span>&#x27; must not be prefixed with &#x27;0&#x27;&quot;</span>, length: lexedLength
       <span class="hljs-keyword">when</span> <span class="hljs-regexp">/^0\d+/</span>.test number

docs/v2/browser-compiler-legacy/coffeescript.js

@@ -21868,13 +21868,6 @@ <h1>CoffeeScript Test Suite</h1>
     0X0
      ^
   '''
-  assertErrorFormat '''
-    10E0
-  ''', '''
-    [stdin]:1:3: error: exponential notation in '10E0' must be indicated with a lowercase 'e'
-    10E0
-      ^
-  '''
   assertErrorFormat '''
     018
   ''', '''
@@ -29359,12 +29352,16 @@ <h2>Another heading</h2>
   eq Number::toString, 0o777['toString']
   eq Number::toString, 0o777.toString
 
-test "#2060: Disallow uppercase radix prefixes and exponential notation", ->
-  for char in ['b', 'o', 'x', 'e']
+test "#2060: Disallow uppercase radix prefixes", ->
+  for char in ['b', 'o', 'x']
     program = "0#{char}0"
     doesNotThrowCompileError program, bare: yes
     throwsCompileError program.toUpperCase(), bare: yes
 
+test "#5164: Allow lowercase and uppercase exponent notation", ->
+  doesNotThrow -> CoffeeScript.compile "0e0", bare: yes
+  doesNotThrow -> CoffeeScript.compile "0E0", bare: yes
+
 test "#2224: hex literals with 0b or B or E", ->
   eq 176, 0x0b0
   eq 177, 0x0B1

docs/v2/browser-compiler-modern/coffeescript.js

@@ -270,9 +270,6 @@ exports.Lexer = class Lexer
     switch
       when /^0[BOX]/.test number
         @error "radix prefix in '#{number}' must be lowercase", offset: 1
-      when /^(?!0x).*E/.test number
-        @error "exponential notation in '#{number}' must be indicated with a lowercase 'e'",
-          offset: number.indexOf('E')
       when /^0\d*[89]/.test number
         @error "decimal literal '#{number}' must not be prefixed with '0'", length: lexedLength
       when /^0\d+/.test number

docs/v2/test.html

@@ -806,13 +806,6 @@ test "invalid numbers", ->
     0X0
      ^
   '''
-  assertErrorFormat '''
-    10E0
-  ''', '''
-    [stdin]:1:3: error: exponential notation in '10E0' must be indicated with a lowercase 'e'
-    10E0
-      ^
-  '''
   assertErrorFormat '''
     018
   ''', '''

lib/coffeescript-browser-compiler-legacy/coffeescript.js

@@ -66,12 +66,16 @@ test "Python-style octal literal notation '0o777'", ->
   eq Number::toString, 0o777['toString']
   eq Number::toString, 0o777.toString
 
-test "#2060: Disallow uppercase radix prefixes and exponential notation", ->
-  for char in ['b', 'o', 'x', 'e']
+test "#2060: Disallow uppercase radix prefixes", ->
+  for char in ['b', 'o', 'x']
     program = "0#{char}0"
     doesNotThrowCompileError program, bare: yes
     throwsCompileError program.toUpperCase(), bare: yes
 
+test "#5164: Allow lowercase and uppercase exponent notation", ->
+  doesNotThrow -> CoffeeScript.compile "0e0", bare: yes
+  doesNotThrow -> CoffeeScript.compile "0E0", bare: yes
+
 test "#2224: hex literals with 0b or B or E", ->
   eq 176, 0x0b0
   eq 177, 0x0B1