Update constant highlighting rules.

We consider something to be a "special constant" if it starts with
"enough" (2 or more in this case) upper-case letters. Any leading
underscores are ignored for the purpose of this definition. Also any
number of underscores and digits are allowed in between the first 2
upper-case letters. To fully satisfy the requirement, the "leading" 2
upper-case letters must be followed by only upper-case letters or
digits until the first underscore.

Author: vpetrovykh

Diff for: grammars/MagicPython.cson

@@ -437,8 +437,13 @@ repository:
     match: '''
       (?x)
         \\b
+          # we want to see "enough", meaning 2 or more upper-case
+          # letters in the beginning of the constant
+          #
+          # for more details refer to:
+          #   https://github.com/MagicStack/MagicPython/issues/42
           (
-            _* [[:upper:]]{2}
+            _* [[:upper:]] [_\\d]* [[:upper:]]
           )
           [[:upper:]\\d]* (_\\w*)?
         \\b

Diff for: grammars/MagicPython.tmLanguage

@@ -662,8 +662,13 @@
         <key>match</key>
         <string>(?x)
   \b
+    # we want to see "enough", meaning 2 or more upper-case
+    # letters in the beginning of the constant
+    #
+    # for more details refer to:
+    #   https://github.com/MagicStack/MagicPython/issues/42
     (
-      _* [[:upper:]]{2}
+      _* [[:upper:]] [_\d]* [[:upper:]]
     )
     [[:upper:]\d]* (_\w*)?
   \b

Diff for: grammars/src/MagicPython.syntax.yaml

@@ -448,8 +448,13 @@ repository:
     match: |
       (?x)
         \b
+          # we want to see "enough", meaning 2 or more upper-case
+          # letters in the beginning of the constant
+          #
+          # for more details refer to:
+          #   https://github.com/MagicStack/MagicPython/issues/42
           (
-            _* [[:upper:]]{2}
+            _* [[:upper:]] [_\d]* [[:upper:]]
           )
           [[:upper:]\d]* (_\w*)?
         \b

Diff for: test/atom-spec/python-spec.js

@@ -5025,6 +5025,39 @@ describe("Grammar Tests", function() {
       expect(tokens[1][12].scopes).toEqual(["source.python"]);
     });
 
+  it("test/expressions/const3.py", 
+    function() {
+      tokens = grammar.tokenizeLines("T61STRING = 20\nT61_STRING\nT_STRING\n_T_S_T_R_I_N_G_\nA_CLASS\n\n# not enough upper-case letters in the beginning\n_T_s_TRING\nA_Class")
+      expect(tokens[0][0].value).toBe("T61STRING");
+      expect(tokens[0][0].scopes).toEqual(["source.python","constant.other.caps.python"]);
+      expect(tokens[0][1].value).toBe(" ");
+      expect(tokens[0][1].scopes).toEqual(["source.python"]);
+      expect(tokens[0][2].value).toBe("=");
+      expect(tokens[0][2].scopes).toEqual(["source.python","keyword.operator.assignment.python"]);
+      expect(tokens[0][3].value).toBe(" ");
+      expect(tokens[0][3].scopes).toEqual(["source.python"]);
+      expect(tokens[0][4].value).toBe("20");
+      expect(tokens[0][4].scopes).toEqual(["source.python","constant.numeric.dec.python"]);
+      expect(tokens[1][0].value).toBe("T61_STRING");
+      expect(tokens[1][0].scopes).toEqual(["source.python","constant.other.caps.python"]);
+      expect(tokens[2][0].value).toBe("T_STRING");
+      expect(tokens[2][0].scopes).toEqual(["source.python","constant.other.caps.python"]);
+      expect(tokens[3][0].value).toBe("_T_S_T_R_I_N_G_");
+      expect(tokens[3][0].scopes).toEqual(["source.python","constant.other.caps.python"]);
+      expect(tokens[4][0].value).toBe("A_CLASS");
+      expect(tokens[4][0].scopes).toEqual(["source.python","constant.other.caps.python"]);
+      expect(tokens[5][0].value).toBe("");
+      expect(tokens[5][0].scopes).toEqual(["source.python"]);
+      expect(tokens[6][0].value).toBe("#");
+      expect(tokens[6][0].scopes).toEqual(["source.python","comment.line.number-sign.python","punctuation.definition.comment.python"]);
+      expect(tokens[6][1].value).toBe(" not enough upper-case letters in the beginning");
+      expect(tokens[6][1].scopes).toEqual(["source.python","comment.line.number-sign.python"]);
+      expect(tokens[7][0].value).toBe("_T_s_TRING");
+      expect(tokens[7][0].scopes).toEqual(["source.python"]);
+      expect(tokens[8][0].value).toBe("A_Class");
+      expect(tokens[8][0].scopes).toEqual(["source.python"]);
+    });
+
   it("test/expressions/expr1.py", 
     function() {
       tokens = grammar.tokenizeLines("~a + b @ c ^ d // e % f & e and not g or h")

Diff for: test/expressions/const3.py

@@ -0,0 +1,27 @@
+T61STRING = 20
+T61_STRING
+T_STRING
+_T_S_T_R_I_N_G_
+A_CLASS
+
+# not enough upper-case letters in the beginning
+_T_s_TRING
+A_Class
+
+
+
+
+T61STRING     : constant.other.caps.python, source.python
+              : source.python
+=             : keyword.operator.assignment.python, source.python
+              : source.python
+20            : constant.numeric.dec.python, source.python
+T61_STRING    : constant.other.caps.python, source.python
+T_STRING      : constant.other.caps.python, source.python
+_T_S_T_R_I_N_G_ : constant.other.caps.python, source.python
+A_CLASS       : constant.other.caps.python, source.python
+              : source.python
+#             : comment.line.number-sign.python, punctuation.definition.comment.python, source.python
+ not enough upper-case letters in the beginning : comment.line.number-sign.python, source.python
+_T_s_TRING    : source.python
+A_Class       : source.python