isl_stream: maintain private ungetc buffer

We may want to unget more than one character.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/include/isl/stream.h b/include/isl/stream.h
index 33d0ffe..4a9fae8 100644 (file)
--- a/include/isl/stream.h
+++ b/include/isl/stream.h
@@ -60,6 +60,8 @@ struct isl_stream {
        size_t          size;
        size_t          len;
        int             c;
+       int             un[5];
+       int             n_un;
 
        struct isl_token        *tokens[5];
        int             n_token;

diff --git a/isl_stream.c b/isl_stream.c
index 09ef60d..bb0f817 100644 (file)
--- a/isl_stream.c
+++ b/isl_stream.c
@@ -127,6 +127,7 @@ static struct isl_stream* isl_stream_new(struct isl_ctx *ctx)
        s->col = 0;
        s->eof = 0;
        s->c = -1;
+       s->n_un = 0;
        for (i = 0; i < 5; ++i)
                s->tokens[i] = NULL;
        s->n_token = 0;
@@ -164,6 +165,8 @@ static int stream_getc(struct isl_stream *s)
        int c;
        if (s->eof)
                return -1;
+       if (s->n_un)
+               return s->c = s->un[--s->n_un];
        if (s->file)
                c = fgetc(s->file);
        else {
@@ -200,10 +203,8 @@ static int isl_stream_getc(struct isl_stream *s)
 
 static void isl_stream_ungetc(struct isl_stream *s, int c)
 {
-       if (s->file)
-               ungetc(c, s->file);
-       else
-               --s->str;
+       isl_assert(s->ctx, s->n_un < 5, return);
+       s->un[s->n_un++] = c;
        s->c = -1;
 }