From e2d629f841375f73c58fcc2fd506bcdb8740ac0e Mon Sep 17 00:00:00 2001
From: Wim Hueskes <git@wimhueskes.eu>
Date: Mon, 18 Apr 2016 22:21:49 +0200
Subject: [PATCH 5/6] add modulo (%) operator

---
 panel-plugin/eval.c      |  5 ++++-
 panel-plugin/grammar.txt |  2 +-
 panel-plugin/lexer.c     |  2 +-
 panel-plugin/parser.c    |  7 +++++--
 panel-plugin/parsetree.h |  1 +
 tests/Makefile.am        |  1 +
 tests/test-modulo.awk    | 15 +++++++++++++++
 7 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100755 tests/test-modulo.awk

diff --git a/panel-plugin/eval.c b/panel-plugin/eval.c
index e678e48..0d9a96a 100644
--- a/panel-plugin/eval.c
+++ b/panel-plugin/eval.c
@@ -103,6 +103,9 @@ static double eval(node_t *parsetree)
         case OP_DIV:
             r = left / right;
             break;
+        case OP_MODULO:
+            r = fmod(left, right);
+            break;
         case OP_POW:
             r = pow(left, right);
             break;
@@ -118,7 +121,7 @@ static double eval(node_t *parsetree)
         arg = eval(parsetree->right);
         r = parsetree->val.fun(arg);
         break;
-        
+
     default:
         g_assert_not_reached();
     }
diff --git a/panel-plugin/grammar.txt b/panel-plugin/grammar.txt
index fa1b6f0..fb11afa 100644
--- a/panel-plugin/grammar.txt
+++ b/panel-plugin/grammar.txt
@@ -19,7 +19,7 @@ pow             ->      ( expr )  |  function ( expr )  |  constant |  NUM
 
 add_op          ->      +  |  -
 
-mult_op         ->      *  |  /
+mult_op         ->      *  |  /  |  %
 
 pow_op          ->      ^  |  **
 
diff --git a/panel-plugin/lexer.c b/panel-plugin/lexer.c
index bd39316..a3b6c99 100644
--- a/panel-plugin/lexer.c
+++ b/panel-plugin/lexer.c
@@ -24,7 +24,7 @@
 
 static gboolean isoperator(int c)
 {
-    if (c == '+' || c == '-' || c == '*' || c == '/' || c == '^')
+    if (c == '+' || c == '-' || c == '*' || c == '/' || c == '%' || c == '^')
         return TRUE;
     else
         return FALSE;
diff --git a/panel-plugin/parser.c b/panel-plugin/parser.c
index 5ae1bbb..cc91ec8 100644
--- a/panel-plugin/parser.c
+++ b/panel-plugin/parser.c
@@ -121,7 +121,7 @@ static gboolean is_mult_op(char op)
     /*
     return op[0] == '/' || (op[0] == '*' && op[1] == '\0')
     */
-    return op == '/' || op == '*';
+    return op == '/' || op == '*' || op == '%';
 }
 
 /*
@@ -388,8 +388,11 @@ static node_t *get_factortail(token_stack_t *stack, node_t *left_expr, GError **
     case '/':
         op->val.op = OP_DIV;
         break;
+    case '%':
+        op->val.op = OP_MODULO;
+        break;
     default:
-        set_error(err, "Expected '*' or '/'", token);
+        set_error(err, "Expected '*', '/' or '%'", token);
         g_free(op);
         return left_expr;
     }
diff --git a/panel-plugin/parsetree.h b/panel-plugin/parsetree.h
index a0f8ff8..2df1c2a 100644
--- a/panel-plugin/parsetree.h
+++ b/panel-plugin/parsetree.h
@@ -26,6 +26,7 @@ typedef enum { NODE_OPERATOR, NODE_NUMBER, NODE_FUNCTION } node_type_t;
 typedef enum { OP_PLUS, OP_MINUS,
                OP_UMINUS,
                OP_TIMES, OP_DIV,
+               OP_MODULO,
                OP_POW } operator_type_t;
 
 typedef struct _node_t {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 1b74a74..2f11daa 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -6,6 +6,7 @@ EXTRA_DIST =								\
 TESTS = 								\
 	test-simple-expr.awk						\
 	test-minus.awk							\
+	test-modulo.awk							\
 	test-e-notation.awk						\
 	test-abs.awk							\
 	test-sqrt.awk							\
diff --git a/tests/test-modulo.awk b/tests/test-modulo.awk
new file mode 100755
index 0000000..792f2ef
--- /dev/null
+++ b/tests/test-modulo.awk
@@ -0,0 +1,15 @@
+#!/usr/bin/awk -f
+
+function abs(x) {
+    return (x < 0) ? -x : x
+}
+
+BEGIN{
+    expr = "'1 + 27 % 5 * 3 + -3 % 2'"
+    "../panel-plugin/calctest " expr | getline res
+    if (abs(res - 6) > 1.0e-14) {
+        print res
+        exit 1
+    } else
+        exit 0
+}
-- 
2.1.4