Allow enabling/disabling of peg module.

Use compiler define -DJANET_NO_PEG to turn off the peg module.

README.md

@@ -1,7 +1,7 @@
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 <img src="https://raw.githubusercontent.com/janet-lang/janet/master/assets/janet-w200.png" alt="Janet logo" width=200 align="left">

src/core/corelib.c

@@ -753,7 +753,9 @@ JanetTable *janet_core_env(void) {
     janet_lib_debug(env);
     janet_lib_string(env);
     janet_lib_marsh(env);
+#ifdef JANET_PEG
     janet_lib_peg(env);
+#endif
 #ifdef JANET_ASSEMBLER
     janet_lib_asm(env);
 #endif

src/core/peg.c

@@ -20,6 +20,8 @@
 * IN THE SOFTWARE.
 */
 
+#ifdef JANET_PEG
+
 #ifndef JANET_AMALG
 #include <janet/janet.h>
 #include <string.h>
@@ -1105,3 +1107,5 @@ static const JanetReg peg_cfuns[] = {
 void janet_lib_peg(JanetTable *env) {
     janet_core_cfuns(env, NULL, peg_cfuns);
 }
+
+#endif /* ifdef JANET_PEG */

src/include/janet/janet.h

@@ -123,6 +123,11 @@ extern "C" {
 #define JANET_ASSEMBLER
 #endif
 
+/* Enable or disable the peg module */
+#ifndef JANET_NO_PEG
+#define JANET_PEG
+#endif
+
 /* How to export symbols */
 #ifndef JANET_API
 #ifdef JANET_WINDOWS