1 files changed, 99 insertions, 0 deletions
diff --git a/src/io.c b/src/io.c
new file mode 100644
index 0000000..5cd5e86
--- /dev/null
+++ b/src/io.c
@@ -0,0 +1,99 @@
+struct SourceLocation {
+    const char* filename;
+    int line;
+};
+typedef struct SourceLocation SourceLocation;
+
+struct InFile {
+    const char* buf;
+    int pos;
+    SourceLocation loc;
+};
+typedef struct InFile InFile;
+
+InFile* infile_open(const char* filename) {
+    FILE* in;
+    if (strcmp(filename, "-") == 0) {
+        in = stdin;
+    } else {
+        in = fopen(filename, "rb");
+    }
+    if (!in) {
+        return NULL;
+    }
+
+    size_t buf_size = 1024 * 10;
+    char* buf = calloc(buf_size, sizeof(char));
+    char* cur = buf;
+    char* tmp = calloc(1024, sizeof(char));
+
+    while (fgets(tmp, 1024, in)) {
+        size_t len = strlen(tmp);
+        size_t used_size = cur - buf;
+
+        if (buf_size <= used_size + len) {
+            size_t old_size = buf_size;
+            buf_size *= 2;
+            buf = realloc(buf, buf_size);
+            memset(buf + old_size, 0, buf_size - old_size);
+            cur = buf + used_size;
+        }
+
+        memcpy(cur, tmp, len);
+        cur += len;
+    }
+    fclose(in);
+
+    InFile* in_file = calloc(1, sizeof(InFile));
+    in_file->buf = buf;
+    in_file->loc.filename = filename;
+    in_file->loc.line = 1;
+    return in_file;
+}
+
+BOOL infile_eof(InFile* f) {
+    return f->buf[f->pos] == '\0';
+}
+
+char infile_peek_char(InFile* f) {
+    char c = f->buf[f->pos];
+
+    // Skip a pair of backslash and new-line.
+    if (c == '\\') {
+        char c2 = f->buf[f->pos + 1];
+        // C23: 5.1.1.2
+        // A source file that is not empty shall end in a new-line character, which shall not be immediately preceded by
+        // a backslash character before any such splicing takes place.
+        if (c2 == '\0') {
+            fatal_error("%s:%d: <new-line> expected, but got <eof>", f->loc.filename, f->loc.line);
+        }
+        // TODO: crlf
+        if (c2 == '\r' || c2 == '\n') {
+            f->pos += 2;
+            return infile_peek_char(f);
+        }
+    }
+
+    // Normalize new-line.
+    // TODO: crlf
+    if (c == '\r')
+        c = '\n';
+    return c;
+}
+
+char infile_next_char(InFile* f) {
+    char c = infile_peek_char(f);
+    ++f->pos;
+    if (c == '\n')
+        ++f->loc.line;
+    return c;
+}
+
+BOOL infile_consume_if(InFile* f, char expected) {
+    if (infile_peek_char(f) == expected) {
+        infile_next_char(f);
+        return TRUE;
+    } else {
+        return FALSE;
+    }
+}