Implemented simple (read-only) (ungetc-able) string-stream

Refactored the stream interface and implemented a simple
stringstream. Now have working filestream and stringstream. Next up is
make eval read "(repl)" from stringstream.

.gitignore

@@ -23,3 +23,4 @@ TAGS
 /src/vm/cpp_vm.d
 /src/vm/test/test_context.d
 /tlisp
+/test/test_stringstream

src/ast-walker/filestream.c

@@ -0,0 +1,33 @@
+#include "filestream.h"
+
+int filestream_getc(STREAM *stream);
+int filestream_ungetc(int ch, STREAM *stream);
+int filestream_flush(STREAM *stream);
+int filestream_close(STREAM *stream);
+
+int make_filestream(STREAM *stream, FILE *f) {
+  stream->payload = f;
+  stream->fgetc_fun = filestream_getc;
+  stream->ungetc_fun = filestream_ungetc;
+  stream->flush_fun = filestream_flush;
+  stream->close_fun = filestream_close;
+  return 1;
+}
+
+int filestream_getc(STREAM *stream) {
+  return fgetc((FILE *)stream->payload);
+}
+
+int filestream_ungetc(int ch, STREAM *stream) {
+  return ungetc(ch, (FILE *)stream->payload);
+}
+
+int filestream_flush(STREAM *stream) {
+  return fflush((FILE *)stream->payload);
+}
+
+int filestream_close(STREAM *stream) {
+  FILE *f = (FILE *)stream->payload;
+  stream->payload = NULL;
+  return fclose(f);
+}

src/ast-walker/filestream.h

@@ -0,0 +1,9 @@
+#ifndef _FILESTREAM_H
+#define _FILESTREAM_H 1
+
+#include <stdio.h>
+#include "t_stream.h"
+
+int make_filestream(STREAM *stream, FILE *f);
+
+#endif /* _FILESTREAM_H */

src/ast-walker/memory.c

@@ -33,6 +33,11 @@ void *malloc_or_bail(size_t bytes) {
   return tmp;
 }
 
+/* Off-heap free. */
+void free_malloced(void *ptr) {
+  free(ptr);
+}
+
 /* On-heap malloc that only returns if it succeeds */
 void *mem_sys_safe_alloc(size_t bytes) {
   void *t;

src/ast-walker/memory.h

@@ -5,6 +5,7 @@
 
 void *mem_sys_safe_alloc(size_t bytes);
 void *malloc_or_bail(size_t bytes);
+void free_malloced(void *ptr);
 void *u8_new(size_t bytes);
 
 #define new(type) ((type *)mem_sys_safe_alloc(sizeof(type)/sizeof(char)))

src/ast-walker/stringstream.c

@@ -0,0 +1,71 @@
+#include "stringstream.h"
+
+#include <string.h>
+#include <stdio.h>
+
+#include "memory.h"
+
+int stringstream_getc(STREAM *stream);
+int stringstream_ungetc(int ch, STREAM *stream);
+int stringstream_flush(STREAM *stream);
+int stringstream_close(STREAM *stream);
+
+typedef struct string_info {
+  char *str;
+  size_t len;
+  size_t index;
+} string_info;
+
+int make_stringstream(STREAM *stream, const char *str, size_t size) {
+  char *target;
+  string_info *s = new_malloc(string_info);
+
+  /* This will at most trigger a read overflow + pagefault. Sweet */
+  if(strlen(str) >= size) { /* str + '\0' must fit in size */
+    memset(stream, 0, sizeof(STREAM)/sizeof(char));
+    return 0;
+  } else if (size < 1) {
+    memset(stream, 0, sizeof(STREAM)/sizeof(char));
+    return 0;
+  }
+
+  target = malloc_or_bail(size);
+  strcpy(target, str); // we got here, len(target) >= len(str + 1) 
+  s->len = size-1;
+  s->index = 0;
+  s->str = target;
+
+  stream->payload = s;
+
+  stream->fgetc_fun = stringstream_getc;
+  stream->ungetc_fun = stringstream_ungetc;
+  stream->flush_fun = stringstream_flush;
+  stream->close_fun = stringstream_close;
+  return 1;
+}
+
+int stringstream_getc(STREAM *stream) {
+  string_info *s = (string_info *)stream->payload;
+  if (s->index >= s->len)
+    return EOF;
+  return (int)((unsigned char)*(s->str + s->index++));
+}
+
+int stringstream_ungetc(int ch, STREAM *stream) {
+  string_info *s = (string_info *)stream->payload;
+  if (s->index <= 0)
+    return EOF;
+
+  *(s->str + --(s->index)) = (char)ch;
+  return ch;
+}
+
+int stringstream_flush(STREAM *stream) {
+  return 1;
+}
+
+int stringstream_close(STREAM *stream) {
+  free_malloced(((string_info *)stream->payload)->str);
+  free_malloced(stream->payload);
+  return 1;
+}

src/ast-walker/stringstream.h

@@ -0,0 +1,10 @@
+#ifndef _STRINGSTREAM_H
+#define _STRINGSTREAM_H 1
+
+#include <stdlib.h>
+
+#include "t_stream.h"
+
+int make_stringstream(STREAM *stream, const char *str, size_t size);
+
+#endif /* _STRINGSTREAM_H */

src/ast-walker/t_stream.c

@@ -1,9 +1,5 @@
 #include "t_stream.h"
 
-int filestream_getc(STREAM *stream);
-int filestream_ungetc(int ch, STREAM *stream);
-int filestream_flush(STREAM *stream);
-int filestream_close(STREAM *stream);
 
 int stream_getc(STREAM *stream) {
   return (stream->fgetc_fun)(stream);
@@ -20,30 +16,3 @@ int stream_flush(STREAM *stream) {
 int stream_close(STREAM *stream) {
   return (stream->close_fun)(stream);
 }
-
-STREAM *make_filestream(STREAM *stream, FILE *f) {
-  stream->payload = f;
-  stream->fgetc_fun = filestream_getc;
-  stream->ungetc_fun = filestream_ungetc;
-  stream->flush_fun = filestream_flush;
-  stream->close_fun = filestream_close;
-  return stream;
-}
-
-int filestream_getc(STREAM *stream) {
-  return fgetc((FILE *)stream->payload);
-}
-
-int filestream_ungetc(int ch, STREAM *stream) {
-  return ungetc(ch, (FILE *)stream->payload);
-}
-
-int filestream_flush(STREAM *stream) {
-  return fflush((FILE *)stream->payload);
-}
-
-int filestream_close(STREAM *stream) {
-  FILE *f = (FILE *)stream->payload;
-  stream->payload = NULL;
-  return fclose(f);
-}

src/ast-walker/t_stream.h

@@ -14,7 +14,4 @@ int stream_ungetc(int ch, STREAM *stream);
 int stream_flush(STREAM *stream);
 int stream_close(STREAM *stream);
 
-#include <stdio.h>
-STREAM *make_filestream(STREAM *stream, FILE *f);
-
 #endif /* _T_STREAM_H */

src/ast-walker/token.c

@@ -5,6 +5,7 @@
 #include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 #include "errors.h"
 

test/test_stringstream.c

@@ -0,0 +1,47 @@
+#include "../src/ast-walker/stringstream.c"
+#include "../src/ast-walker/memory.h"
+#include "../src/ast-walker/memory.c"
+#include "../src/ast-walker/t_stream.h"
+#include "../src/ast-walker/t_stream.c"
+
+#include <string.h>
+
+int main(void) {
+  STREAM s;
+  const char *tmp = "hej pa dig";
+  int ch, i;
+
+  make_stringstream(&s, tmp, strlen(tmp)+1);
+
+  while((ch = stream_getc(&s)) != EOF)
+    putchar(ch);
+
+  printf("END\n");
+  stream_close(&s);
+
+  printf("%s\n", tmp);
+
+  make_stringstream(&s, tmp, strlen(tmp)+1);
+  for (i = 0; i < 4; i++)
+    ch = stream_getc(&s);
+
+  stream_ungetc('.', &s);
+  stream_ungetc('J', &s);
+  stream_ungetc('O', &s);
+  stream_ungetc('H', &s);
+
+  ch = stream_ungetc('2', &s);
+  if (ch != EOF) {
+    printf("Should get EOF\n");
+  } else {
+    printf("All ok, got EOF\n");
+  }
+
+  printf("UNCHANGED: %s\n", tmp);
+
+  while((ch = stream_getc(&s)) != EOF)
+    putchar(ch);
+  printf("END\n");
+
+  stream_close(&s);
+}