split some things out

erow.c

@@ -0,0 +1,117 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+#include "defs.h"
+
+
+int
+erow_render_to_cursor(struct erow *row, int cx)
+{
+	int	rx = 0;
+	int	j;
+
+	for (j = 0; j < cx; j++) {
+		if (row->line[j] == '\t') {
+			rx += (TAB_STOP-1) - (rx%TAB_STOP);
+		}
+		rx++;
+	}
+
+	return rx;
+}
+
+
+int
+erow_cursor_to_render(struct erow *row, int rx)
+{
+	int	cur_rx = 0;
+	int	curx = 0;
+
+	for (curx = 0; curx < row->size; curx++) {
+		if (row->line[curx] == '\t') {
+			cur_rx += (TAB_STOP - 1) - (cur_rx % TAB_STOP);
+		}
+		cur_rx++;
+
+		if (cur_rx > rx) {
+			break;
+		}
+	}
+
+	return curx;
+}
+
+
+void
+erow_update(struct erow *row)
+{
+	int	i = 0, j;
+	int	tabs = 0;
+
+	/*
+	 * TODO(kyle): I'm not thrilled with this double-render.
+	 */
+	for (j = 0; j < row->size; j++) {
+		if (row->line[j] == '\t') {
+			tabs++;
+		}
+	}
+
+	free(row->render);
+	row->render = NULL;
+	row->render = malloc(row->size + (tabs * (TAB_STOP-1)) + 1);
+	assert(row->render != NULL);
+
+	for (j = 0; j < row->size; j++) {
+		if (row->line[j] == '\t') {
+			do {
+				row->render[i++] = ' ';
+			} while ((i % TAB_STOP) != 0);
+		} else {
+			row->render[i++] = row->line[j];
+		}
+	}
+
+	row->render[i] = '\0';
+	row->rsize = i;
+}
+
+
+void
+erow_insert(int at, char *s, int len)
+{
+	if (at < 0 || at > editor.nrows) {
+		return;
+	}
+
+	editor.row = realloc(editor.row, sizeof(struct erow) * (editor.nrows + 1));
+	assert(editor.row != NULL);
+
+	if (at < editor.nrows) {
+		memmove(&editor.row[at+1], &editor.row[at],
+		    sizeof(struct erow) * (editor.nrows - at + 1));
+	}
+
+	editor.row[at].size = len;
+	editor.row[at].line = malloc(len+1);
+	memcpy(editor.row[at].line, s, len);
+	editor.row[at].line[len] = '\0';
+
+	editor.row[at].rsize = 0;
+	editor.row[at].render = NULL;
+
+	erow_update(&editor.row[at]);
+	editor.nrows++;
+}
+
+
+void
+erow_free(struct erow *row)
+{
+	free(row->render);
+	free(row->line);
+	row->render = NULL;
+	row->line  = NULL;
+}