From 681fb9aa0fd7134daffd7494fa320ea3a7ef67c7 Mon Sep 17 00:00:00 2001
From: Lewis Van Winkle <lv@codeplea.com>
Date: Tue, 23 Feb 2016 17:29:03 -0600
Subject: [PATCH] Allow empty parens for function0.

---
 README.md  |  2 +-
 tinyexpr.c | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 5e1361e..2fd59db 100644
--- a/README.md
+++ b/README.md
@@ -219,7 +219,7 @@ TinyExpr parses the following grammar:
     <term>      =    <factor> {("*" | "/" | "%") <factor>}
     <factor>    =    <power> {"^" <power>}
     <power>     =    {("-" | "+")} <base>
-    <base>      =    <constant> | <variable> | <function-1> <power> | <function-2> "(" <expr> "," <expr> ")" | "(" <list> ")"
+    <base>      =    <constant> | <variable> | <function-0> {"(" ")"} | <function-1> <power> | <function-2> "(" <expr> "," <expr> ")" | "(" <list> ")"
 
 In addition, whitespace between tokens is ignored.
 
diff --git a/tinyexpr.c b/tinyexpr.c
index 12c8b3a..4f3bee2 100644
--- a/tinyexpr.c
+++ b/tinyexpr.c
@@ -205,7 +205,7 @@ static te_expr *expr(state *s);
 static te_expr *power(state *s);
 
 static te_expr *base(state *s) {
-    /* <base>      =    <constant> | <variable> | <function-1> <power> | <function-2> "(" <expr> "," <expr> ")" | "(" <list> ")" */
+    /* <base>      =    <constant> | <variable> | <function-0> {"(" ")"} | <function-1> <power> | <function-2> "(" <expr> "," <expr> ")" | "(" <list> ")" */
     te_expr *ret;
 
     switch (s->type) {
@@ -225,6 +225,14 @@ static te_expr *base(state *s) {
             ret = new_expr(TE_FUNCTION0, 0, 0);
             ret->f0 = s->f0;
             next_token(s);
+            if (s->type == TOK_OPEN) {
+                next_token(s);
+                if (s->type != TOK_CLOSE) {
+                    s->type = TOK_ERROR;
+                } else {
+                    next_token(s);
+                }
+            }
             break;
 
         case TOK_FUNCTION1: