[gnome-calculator] Support latex-style multipy (fixes #164)

[Robert Roth <robertroth src gnome org>]

commit c0ec19b8d80b5498c1d873f46fe694aedbae8e4a
Author: Robert Roth <robert roth off gmail com>
Date:   Thu Jun 4 17:26:01 2020 +0300

    Support latex-style multipy (fixes #164)

 lib/equation-lexer.vala | 4 +++-
 lib/math-equation.vala  | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/lib/equation-lexer.vala b/lib/equation-lexer.vala
index 6a5b8d92..6c2a5f02 100644
--- a/lib/equation-lexer.vala
+++ b/lib/equation-lexer.vala
@@ -151,7 +151,7 @@ public class PreLexer : Object
         if (c == '"')
             return LexerTokenType.PL_SECOND;
 
-        if (c.isalpha () || c == '_')
+        if (c.isalpha () || c == '_' || c == '\\')
             return LexerTokenType.PL_LETTER;
 
         if (c == '∧')
@@ -709,6 +709,8 @@ public class Lexer : Object
             return insert_token (LexerTokenType.MOD);
         if (name == "and")
             return insert_token (LexerTokenType.AND);
+        if (name == "\\cdot")
+            return insert_token (LexerTokenType.MULTIPLY);
         if (name == "or")
             return insert_token (LexerTokenType.OR);
         if (name == "xor")
diff --git a/lib/math-equation.vala b/lib/math-equation.vala
index 46c91c08..ae71e706 100644
--- a/lib/math-equation.vala
+++ b/lib/math-equation.vala
@@ -798,7 +798,7 @@ public class MathEquation : Gtk.SourceBuffer
         /* Show the number in the user chosen format */
         var text = serializer.to_string (x);
 
-        this.history_signal (get_current_state ().expression, x, number_base, representation_base); /*emits 
signal to enter a new entry into history-view */
+        this.history_signal (get_current_state ().expression.replace ("\\cdot", "×"), x, number_base, 
representation_base); /*emits signal to enter a new entry into history-view */
         set_text (text, -1);
         state.ans = x;