From 94dc8ca3313e14792058d3d16f8778248f43538d Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Tue, 20 Aug 2019 11:55:11 -0400
Subject: [PATCH] Backspace to previous line

---
 kilo.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/kilo.c b/kilo.c
index e77bb73..9fedc36 100644
--- a/kilo.c
+++ b/kilo.c
@@ -321,6 +321,24 @@ void editorAppendRow(char *s, size_t len)
 	E.dirty++;
 }
 
+void editorFreeRow(erow *row)
+{
+	free(row->render);
+	free(row->chars);
+}
+
+void editorDelRow(int at)
+{
+	if (at < 0 || at >= E.numrows)
+	{
+		return;
+	}
+	editorFreeRow(&E.row[at]);
+	memmove(&E.row[at], &E.row[at + 1], sizeof(erow) * (E.numrows - at - 1));
+	E.numrows--;
+	E.dirty++;
+}
+
 void editorRowInsertChar(erow *row, int at, int c)
 {
 	if (at < 0 || at > row->size)
@@ -336,6 +354,16 @@ void editorRowInsertChar(erow *row, int at, int c)
 	E.dirty++;
 }
 
+void editorRowAppendString(erow *row, char *s, size_t len)
+{
+	row->chars = realloc(row->chars, row->size + len + 1);
+	memcpy(&row->chars[row->size], s, len);
+	row->size += len;
+	row->chars[row->size] = '\0';
+	editorUpdateRow(row);
+	E.dirty++;
+}
+
 void editorRowDelChar(erow *row, int at)
 {
 	if (at < 0 || at >= row->size)
@@ -368,12 +396,24 @@ void editorDelChar()
 		return;
 	}
 
+	if (E.cx == 0 && E.cy == 0)
+	{
+		return;
+	}
+
 	erow *row = &E.row[E.cy];
 	if (E.cx > 0)
 	{
 		editorRowDelChar(row, E.cx - 1);
 		E.cx--;
 	}
+	else
+	{
+		E.cx = E.row[E.cy - 1].size;
+		editorRowAppendString(&E.row[E.cy - 1], row->chars, row->size);
+		editorDelRow(E.cy);
+		E.cy--;
+	}
 }
 
 /*** file i/o ***/