fix parser, add functions

main.c

@@ -16,7 +16,6 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
-    parser_init(&parser);
     node = parser_parse(&parser, argv[1], "x");
 
     if (!node) {

math_functions.c

@@ -20,6 +20,17 @@ MAKE_FUNCTION_1_ARG(atan)
 MAKE_FUNCTION_1_ARG(sinh)
 MAKE_FUNCTION_1_ARG(cosh)
 MAKE_FUNCTION_1_ARG(tanh)
+MAKE_FUNCTION_1_ARG(floor)
+MAKE_FUNCTION_1_ARG(ceil)
+
+static double mf_sgn(const double *args) {
+    if (args[0] < 0.0)
+        return -1.0;
+    else if (args[0] > 0.0)
+        return 1.0;
+    else
+        return 0.0;
+}
 
 static double mf_min(const double *args) {
     if (args[0] < args[1])
@@ -57,6 +68,9 @@ const struct math_function *fns_get(void) {
         { "min",    2,  mf_min      },
         { "max",    2,  mf_max      },
         { "mod",    2,  mf_mod      },
+        { "sgn",    1,  mf_sgn      },
+        { "floor",  1,  mf_floor    },
+        { "ceil",   1,  mf_ceil     },
         { NULL }
     };
 

parser.c

@@ -300,11 +300,8 @@ int parse_n_expressions(struct parser *parser, struct expr_node **out_nodes, siz
     return 1;
 }
 
-void parser_init(struct parser *parser) {
-    error_buffer_init(&parser->eb);
-}
-
 int parser_parse_n(struct parser *parser, const char *str, const char *variable_name, struct expr_node **out_nodes, size_t n) {
+    error_buffer_init(&parser->eb);
     lex_init(&parser->lexer, str, variable_name);
 
     if (!parse_n_expressions(parser, out_nodes, n)) {

parser.h

@@ -9,7 +9,6 @@ struct parser {
     struct error_buffer eb;
 };
 
-void parser_init(struct parser *parser);
 int parser_parse_n(struct parser *parser, const char *str, const char *variable_name, struct expr_node **out_nodes, size_t n);
 struct expr_node *parser_parse(struct parser *parser, const char *str, const char *variable_name);