[gnome-calculator] Fixes 'malformed syntax' when using '@'

[Robert Roth <robertroth src gnome org>]

commit 98b3f5782f53bab2f1c0b14c4b6368a74b462308
Author: harryjrk <martinjirku gmail com>
Date:   Sat May 15 17:20:02 2021 +0200

    Fixes 'malformed syntax' when using '@'
    
    When custom function is specified with '@' for description, Calculator returned malfored syntax.
    This change will add support for description in function definition.
    
    Implements #188

 lib/equation-lexer.vala  | 9 +++++++--
 tests/test-equation.vala | 3 +++
 2 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/lib/equation-lexer.vala b/lib/equation-lexer.vala
index 36e8d9bd..7adb5814 100644
--- a/lib/equation-lexer.vala
+++ b/lib/equation-lexer.vala
@@ -67,7 +67,8 @@ public enum LexerTokenType
     POWER,              /* ^ */
     FACTORIAL,          /* ! */
     PERCENTAGE,         /* % */
-    ARGUMENT_SEPARATOR  /* ; (Function argument separator) */
+    ARGUMENT_SEPARATOR, /* ; (Function argument separator) */
+    FUNC_DESC_SEPARATOR /* @ (Function description separator) */
 }
 
 // FIXME: Merge into lexer
@@ -244,6 +245,9 @@ public class PreLexer : Object
         if (c == ' ' || c == '\r' || c == '\t' || c == '\n')
             return LexerTokenType.PL_SKIP;
 
+        if (c == '@')
+            return LexerTokenType.FUNC_DESC_SEPARATOR;
+
         return LexerTokenType.UNKNOWN;
     }
 }
@@ -395,7 +399,8 @@ public class Lexer : Object
             || type == LexerTokenType.L_R_BRACKET || type == LexerTokenType.R_R_BRACKET || type == 
LexerTokenType.L_S_BRACKET
             || type == LexerTokenType.R_S_BRACKET || type == LexerTokenType.L_C_BRACKET || type == 
LexerTokenType.R_C_BRACKET
             || type == LexerTokenType.ABS || type == LexerTokenType.POWER || type == 
LexerTokenType.FACTORIAL || type == LexerTokenType.PERCENTAGE
-            || type == LexerTokenType.ARGUMENT_SEPARATOR || type == LexerTokenType.SHIFT_LEFT || type == 
LexerTokenType.SHIFT_RIGHT)
+            || type == LexerTokenType.ARGUMENT_SEPARATOR || type == LexerTokenType.SHIFT_LEFT || type == 
LexerTokenType.SHIFT_RIGHT
+            || type == LexerTokenType.FUNC_DESC_SEPARATOR)
             return insert_token (type);
 
         /* [LexerTokenType.PL_SUPER_MINUS][LexerTokenType.PL_SUPER_DIGIT]+ */
diff --git a/tests/test-equation.vala b/tests/test-equation.vala
index 356d8bf1..e9b415f9 100644
--- a/tests/test-equation.vala
+++ b/tests/test-equation.vala
@@ -805,12 +805,15 @@ private void test_custom_functions ()
     test ("sum(sum(sum(1;1);sum(1;1));sum(sum(1;1);sum(1;1)))", "8", ErrorCode.UNKNOWN_FUNCTION);
     test ("sum(x;y)=x+y+1", "0", 0);
     test ("sum(sum(sum(1;1);sum(1;1));sum(sum(1;1);sum(1;1)))", "15", 0);
+    test ("funcWithDescription(x;y;z)=x+y+z @ Description", "0", 0);
+    test ("funcWithDescription(2;3;5)", "10", 0);
 
     function_manager.delete ("func");
     function_manager.delete ("test");
     function_manager.delete ("sum");
     function_manager.delete ("dummy");
     function_manager.delete ("abcd");
+    function_manager.delete ("funcWithDescription");
 }
 
 public int main (string[] args)