From 14cac64019b3425eb40eb82471b0995d62b9a7a2 Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Tue, 10 Jan 2017 10:47:49 +0100
Subject: Auto-scroll on move_forward (and fix fCIS)

---
 buffer.cpp | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

(limited to 'buffer.cpp')

diff --git a/buffer.cpp b/buffer.cpp
index 97c898f..1ace091 100644
--- a/buffer.cpp
+++ b/buffer.cpp
@@ -71,6 +71,10 @@ void Buffer::handleCommand(const Command &cmd){
 		} else {
 			cursor.x++;
 		}
+		if(findCursorInScreen().x==-1){
+			screen.erase(screen.begin());
+			relayoutScreen();
+		}
 	} else if(cmd[0]=="move_backward"){
 		if(cursor.line==0&&cursor.x==0){
 			bel();
@@ -123,7 +127,7 @@ void Buffer::handleCommand(const Command &cmd){
 
 void Buffer::receive(const Command &cmd){
 	handleCommand(cmd);
-	cerr<<"New cursor is (line="<<cursor.line<<", x="<<cursor.x<<")"<<endl;
+	// cerr<<"New cursor is (line="<<cursor.line<<", x="<<cursor.x<<")"<<endl;
 }
 
 static string showChar(char c){
@@ -280,18 +284,31 @@ void Buffer::relayoutScreen(){
 //Returns {-1,-1} if not found
 Buffer::Screenpos Buffer::findCursorInScreen() const {
 	if(screen.size()==0)return {-1,-1};
+	if(cursor.x>tb.lineLen(cursor.line)){
+		THROW("Invalid cursor position: past end of line");
+	}
 	auto lineit=lower_bound(screen.begin(),screen.end(),cursor.line,[this](const ScreenLine &sl,i64 line){
 		return sl.line<line||(sl.line==line&&sl.fromx<=cursor.x);
 	});
 	if(lineit==screen.begin())return {-1,-1};
-	--lineit;
-	const i64 y=distance(screen.begin(),lineit);
-	const vector<Cell> &cells=lineit->cells;
+
+	const i64 y=lineit==screen.end()?screen.size()-1:distance(screen.begin(),lineit)-1;
+	if(screen[y].line!=cursor.line)return {-1,-1}; //cursor is below screen on a new line
+	const vector<Cell> &cells=screen[y].cells;
 	auto chrit=lower_bound(cells.begin(),cells.end(),cursor.x,[](const Cell &cell,i64 x){
 		return cell.linex<x;
 	});
 	const i64 x=distance(cells.begin(),chrit);
-	return {y,x};
+	assert(x<=(i64)cells.size());
+	if(x<(i64)cells.size())return {y,x};
+	if(cells.size()==0){
+		return {y,0};
+	}
+	if(cells.back().linex==cursor.x-1&&cursor.x==tb.lineLen(cursor.line)){
+		return {y,x};
+	} else {
+		return {-1,-1};
+	}
 }
 
 i64 numberWidth(i64 number){
-- 
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