Custom file struct

README.md

@@ -178,9 +178,8 @@ Turns into
 !dlrow olleH
 ```
 
-Things between an `@n` and `@m` tag get processed twice. A double escape char `@@`
-gets escaped into a single escape char `@`. Defining variables in a nest is
-illegal, so
+Things between an `@n` and `@m` tag get processed twice. Defining variables in a
+nest is illegal, so
 
 ```
 @n @@= dynamic_variable @$./generate_variable_value.sh@ @@ @m

src/include/config.h

@@ -6,6 +6,8 @@
 #define NOMINIFY_CHAR '&'
 #define SEPARATOR_CHAR ','
 #define SHELL_CHAR '$'
+#define NEST_START 'n'
+#define NEST_END 'm'
 
 #define ALLOW_SHELL
 

src/include/ncdgfile.h

@@ -0,0 +1,16 @@
+#ifndef HAVE_NCDGFILE
+#define HAVE_NCDGFILE
+
+#include <stdio.h>
+
+struct ncdgfile {
+	int (*putc)(struct ncdgfile *file, int c);
+	int (*puts)(struct ncdgfile *file, char *s);
+	void (*free)(struct ncdgfile *file);
+	void *handle;
+};
+
+struct ncdgfile *file2ncdg(FILE *file);
+struct ncdgfile *stringfile(void);
+
+#endif

src/ncdgfile.c

@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <strings.h>
+#include <ncdgfile.h>
+
+static int fileputc(struct ncdgfile *file, int c);
+static int fileputs(struct ncdgfile *file, char *s);
+static void filefree(struct ncdgfile *file);
+
+static int stringputc(struct ncdgfile *file, int c);
+static int stringputs(struct ncdgfile *file, char *s);
+static void stringfree(struct ncdgfile *file);
+
+struct ncdgfile *file2ncdg(FILE *file) {
+	struct ncdgfile *ret;
+	if ((ret = malloc(sizeof *ret)) == NULL) {
+		return NULL;
+	}
+	ret->putc = fileputc;
+	ret->puts = fileputs;
+	ret->free = filefree;
+	ret->handle = (void *) file;
+	return ret;
+}
+
+struct ncdgfile *stringfile(void) {
+	struct ncdgfile *ret;
+	if ((ret = malloc(sizeof *ret)) == NULL) {
+		goto error1;
+	}
+	if ((ret->handle = (void *) newstring()) == NULL) {
+		goto error2;
+	}
+	ret->putc = stringputc;
+	ret->puts = stringputs;
+	ret->free = stringfree;
+	return ret;
+error2:
+	free(ret);
+error1:
+	return NULL;
+}
+
+static int fileputc(struct ncdgfile *file, int c) {
+	return fputc(c, (FILE *) file->handle) == EOF ? -1 : 0;
+}
+
+static int fileputs(struct ncdgfile *file, char *s) {
+	return fputs(s, (FILE *) file->handle) == EOF ? -1 : 0;
+}
+
+static void filefree(struct ncdgfile *file) {
+	fclose((FILE *) file->handle);
+	free(file);
+}
+
+static int stringputc(struct ncdgfile *file, int c) {
+	return appendchar((struct string *) file->handle, c) ? -1 : 0;
+}
+
+static int stringputs(struct ncdgfile *file, char *s) {
+	long i;
+	for (i = 0; s[i] != '\0'; ++i) {
+		if (appendchar((struct string *) file->handle, s[i])) {
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static void stringfree(struct ncdgfile *file) {
+	freestring((struct string *) file->handle);
+	free(file);
+}

src/parse.c

@@ -157,6 +157,10 @@ autoescapeend:
 				break;
 			}
 #endif
+			case NEST_START:
+				return 0;
+			case NEST_END:
+				return 0;
 			default:
 				fprintf(stderr, "Error in expansion phase: Unknown escape %c%c\n", ESCAPE_CHAR, data->data[i]);
 				return 1;