Added flags to language specifiction. Added optional expect string to language specification. Added some exaple grammars for testing and demos

examples/maths.c

@@ -0,0 +1,47 @@
+#include "../mpc.h"
+
+int main(int argc, char **argv) {
+  
+  mpc_parser_t *Expr  = mpc_new("expression");
+  mpc_parser_t *Prod  = mpc_new("product");
+  mpc_parser_t *Value = mpc_new("value");
+  mpc_parser_t *Maths = mpc_new("maths");
+  
+  mpca_lang(MPC_LANG_PREDICTIVE,
+    "                                                    \
+        expression : <product> (('+' | '-') <product>)*; \
+        product : <value>   (('*' | '/')   <value>)*;    \
+        value : /[0-9]+/ | '(' <expression> ')';         \
+        maths : /^/ <expression> /$/;                    \
+    ",
+    Expr, Prod, Value, Maths);
+  
+  if (argc > 1) {
+    
+    mpc_result_t r;
+    if (mpc_parse_contents(argv[1], Maths, &r)) {
+      mpc_ast_print(r.output);
+      mpc_ast_delete(r.output);
+    } else {
+      mpc_err_print(r.error);
+      mpc_err_delete(r.error);
+    }
+    
+  } else {
+
+    mpc_result_t r;
+    if (mpc_parse_pipe("<stdin>", stdin, Maths, &r)) {
+      mpc_ast_print(r.output);
+      mpc_ast_delete(r.output);
+    } else {
+      mpc_err_print(r.error);
+      mpc_err_delete(r.error);
+    }
+  
+  }
+
+  mpc_cleanup(4, Expr, Prod, Value, Maths);
+  
+  return 0;
+  
+}