[gcalctool] Automatically add missing closing brackets (Bug #615243)

[Robert Ancell <rancell src gnome org>]

commit f578cbeef6888df5f6b5e61d7cdf47a9c7839bb6
Author: Robert Ancell <robert ancell gmail com>
Date:   Fri Apr 23 10:23:39 2010 +1000

    Automatically add missing closing brackets (Bug #615243)

 NEWS                |    2 ++
 src/math-equation.c |   22 +++++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)
---
diff --git a/NEWS b/NEWS
index 4e64e94..540859c 100644
--- a/NEWS
+++ b/NEWS
@@ -34,6 +34,8 @@ Overview of changes in gcalctool 5.31.1
     
     * Add back in undo and redo
 
+    * Automatically add missing closing brackets (Bug #615243)
+
 Overview of changes in gcalctool 5.30.0
 
     * Fix errors in variable exponents (e.g. xy²)
diff --git a/src/math-equation.c b/src/math-equation.c
index c002766..5d46348 100644
--- a/src/math-equation.c
+++ b/src/math-equation.c
@@ -1085,8 +1085,9 @@ void
 math_equation_solve(MathEquation *equation)
 {
     MPNumber z;
-    int result;
-    gchar *text, *error_token = NULL, *message = NULL;
+    gint result, n_brackets = 0;
+    gchar *c, *text, *error_token = NULL, *message = NULL;
+    GString *equation_text;
 
     if (math_equation_is_empty(equation))
         return;
@@ -1101,8 +1102,23 @@ math_equation_solve(MathEquation *equation)
     math_equation_set_number_mode(equation, NORMAL);
 
     text = math_equation_get_equation(equation);
-    result = parse(equation, text, &z, &error_token);
+    equation_text = g_string_new(text);
     g_free(text);
+    /* Count the number of brackets and automatically add missing closing brackets */
+    for (c = equation_text->str; *c; c++) {
+        if (*c == '(')
+            n_brackets++;
+        else if (*c == ')')
+            n_brackets--;
+    }
+    while (n_brackets > 0) {
+        g_string_append_c(equation_text, ')');
+        n_brackets--;
+    }
+  
+
+    result = parse(equation, equation_text->str, &z, &error_token);
+    g_string_free(equation_text, TRUE);
 
     switch (result) {
         case PARSER_ERR_NONE: