Add chapter 6

chapter_06/Makefile

@@ -0,0 +1,13 @@
+MPC_DIR := ../mpc
+
+
+all: parsing
+
+
+%: %.c
+	cc -std=c11 -Wall $@.c ${MPC_DIR}/mpc.c -ledit -o $@
+
+
+.PHONY: clean
+clean:
+	rm -rf parsing

chapter_06/parsing.c

@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "../mpc/mpc.h"
+
+
+/* If we are on Windows compile these functions */
+#ifdef _WIN32
+#include <string.h>
+#include <assert.h>
+
+static char buffer[2048];
+
+/* Fake readline function */
+char* readline(char* prompt) {
+    fputs(prompt, stdout);
+    fgets(buffer, 2048, stdin);
+    char* cpy = malloc(strlen(buffer)+1);
+    assert(cpy != NULL)
+    strcpy(cpy, buffer);
+    cpy[strlen(cpy)-1] = '\0';
+    return cpy;
+}
+
+/* Fake add_history function */
+void add_history(char* unused) {}
+
+/* Otherwise include the editline headers
+   could use __APPLE__ for detection of OSX */
+#else
+#include <editline/readline.h>
+#endif
+
+
+int main(int argc, char const *argv[])
+{
+    /* Create some parsers */
+    mpc_parser_t* Number = mpc_new("number");
+    mpc_parser_t* Operator = mpc_new("operator");
+    mpc_parser_t* Expr = mpc_new("expr");
+    mpc_parser_t* Lispy = mpc_new("lispy");
+
+    /* Define them with the following language */
+    mpca_lang(MPCA_LANG_DEFAULT,
+        "                                                        \
+            number   : /-?[0-9]+/ ;                              \
+            operator : '+' | '-' | '*' | '/' ;                   \
+            expr     : <number> |  '(' <operator> <expr>+ ')' ;  \
+            lispy    : /^/ <operator> <expr>+ /$/ ;              \
+        ",
+        Number, Operator, Expr, Lispy);
+
+    /* Print version and exit information */
+    puts("Lispy version 0.0.0.0.1");
+    puts("Press Ctrl+c to exit\n");
+
+    /* In a never ending loop */
+    while (1) {
+        /* Output our prompt and get input */
+        char* input = readline("lispy> ");
+
+        /* Add input to history */
+        add_history(input);
+
+        /* Attempt to parse the user input */
+        mpc_result_t r;
+        if (mpc_parse("<stdin>", input, Lispy, &r)) {
+            /* On success print the AST */
+            mpc_ast_print(r.output);
+            mpc_ast_delete(r.output);
+        } else {
+            /* Otherwise print the error */
+            mpc_err_print(r.error);
+            mpc_err_delete(r.error);
+        }
+
+        /* Free retrieved input */
+        free(input);
+    }
+
+    /* Undefine and delete our parsers */
+    mpc_cleanup(4, Number, Operator, Expr, Lispy);
+
+    return 0;
+}