Move downward

2 files changed, 101 insertions, 37 deletions

diff --git a/buffer.cpp b/buffer.cpp
index 78f5e16..9b91e43 100644
--- a/buffer.cpp
+++ b/buffer.cpp
@@ -1,5 +1,6 @@
-#include <stdexcept>
+#include <algorithm>
 #include <fstream>
+#include <stdexcept>
 #include <cassert>
 #include <cmath>
 #include <cinttypes>
@@ -15,8 +16,8 @@ using namespace std;
 Buffer::Buffer(Manager *manager)
 	:manager(manager){}
 
-void Buffer::receive(const Command &cmd){
-	//TODO: optimise the renewLayout's in this function
+void Buffer::handleCommand(const Command &cmd){
+	//TODO: optimise the relayoutScreen's in this function
 
 	if(cmd[0]=="open_file"){
 		const string &fname=cmd[1];
@@ -29,67 +30,100 @@ void Buffer::receive(const Command &cmd){
 		tb.read(file);
 	} else if(cmd[0]=="insert_char"){
 		char c=cmd[1][0];
-		if(c=='\n'){
-			assert(false);
-		} else {
-			tb.insert(cursor.line,cursor.x,cmd[1][0]);
-			cursor.x++;
-		}
-		renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+		assert(c!='\n');
+		tb.insert(cursor.line,cursor.x,cmd[1][0]);
+		cursor.x++;
+		relayoutScreen();
 	} else if(cmd[0]=="insert_newline"){
 		tb.insert(cursor.line,cursor.x,'\n');
 		cursor.x=0;
 		cursor.line++;
-		renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+		relayoutScreen();
 	} else if(cmd[0]=="delete_backward"){
 		if(cursor.x==0&&cursor.line==0){
 			bel();
+			return;
+		}
+		if(cursor.x>0){
+			cursor.x--;
+			tb.erase(cursor.line,cursor.x);
 		} else {
-			if(cursor.x>0){
-				cursor.x--;
-				tb.erase(cursor.line,cursor.x);
-			} else {
-				cursor.line--;
-				cursor.x=tb.lineLen(cursor.line);
-				tb.erase(cursor.line,cursor.x);
-			}
-			renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+			cursor.line--;
+			cursor.x=tb.lineLen(cursor.line);
+			tb.erase(cursor.line,cursor.x);
 		}
+		relayoutScreen();
 	} else if(cmd[0]=="delete_forward"){
 		if(cursor.line==tb.numLines()-1&&cursor.x==tb.lineLen(cursor.line)){
 			bel();
-		} else {
-			tb.erase(cursor.line,cursor.x);
-			renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+			return;
 		}
+		tb.erase(cursor.line,cursor.x);
+		relayoutScreen();
 	} else if(cmd[0]=="move_forward"){
 		if(cursor.line==tb.numLines()-1&&cursor.x==tb.lineLen(cursor.line)){
 			bel();
+			return;
+		}
+		if(cursor.x==tb.lineLen(cursor.line)){
+			cursor.x=0;
+			cursor.line++;
 		} else {
-			if(cursor.x==tb.lineLen(cursor.line)){
-				cursor.x=0;
-				cursor.line++;
-			} else {
-				cursor.x++;
-			}
-			renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+			cursor.x++;
 		}
 	} else if(cmd[0]=="move_backward"){
 		if(cursor.line==0&&cursor.x==0){
 			bel();
+			return;
+		}
+		if(cursor.x==0){
+			cursor.line--;
+			cursor.x=tb.lineLen(cursor.line);
 		} else {
-			if(cursor.x==0){
-				cursor.line--;
-				cursor.x=tb.lineLen(cursor.line);
-			} else {
-				cursor.x--;
+			cursor.x--;
+		}
+	} else if(cmd[0]=="move_downward"){
+		Screenpos sp=findCursorInScreen();
+		if(sp.x==-1){
+			bel();
+			return;
+		}
+		if(sp.y==(i64)screen.size()-1){
+			if(screen[sp.y].line==tb.numLines()-1&&
+			   (screen[sp.y].cells.size()==0
+					?tb.lineLen(screen[sp.y].line)==0
+					:screen[sp.y].cells.back().linex==tb.lineLen(screen[sp.y].line)-1)){
+				//so screen[sp.y] contains the end of that logical line
+				if(cursor.x==tb.lineLen(screen[sp.y].line)){
+					bel();
+				} else {
+					cursor.x=tb.lineLen(screen[sp.y].line);
+				}
+				return;
 			}
-			renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+			screen.erase(screen.begin());
+			relayoutScreen();
+		} else {
+			sp.y++;
+		}
+		if(sp.y>=(i64)screen.size()){
+			bel();
+			return;
+		}
+		cursor.line=screen[sp.y].line;
+		if(sp.x>=(i64)screen[sp.y].cells.size()){
+			cursor.x=tb.lineLen(cursor.line);
+		} else {
+			cursor.x=screen[sp.y].cells[sp.x].linex;
 		}
 	} else {
 		THROW("Unknown command");
 	}
-	//cerr<<"New cursor is (line="<<cursor.line<<", x="<<cursor.x<<")"<<endl;
+}
+
+void Buffer::receive(const Command &cmd){
+	handleCommand(cmd);
+	cerr<<"New cursor is (line="<<cursor.line<<", x="<<cursor.x<<")"<<endl;
 }
 
 static string showChar(char c){
@@ -239,6 +273,27 @@ void Buffer::renewLayout(i64 topLine,i64 topPart,i64 width,i64 height){
 	}
 }
 
+void Buffer::relayoutScreen(){
+	renewLayout(screen[0].line,screen[0].part,lastWidth,lastHeight);
+}
+
+//Returns {-1,-1} if not found
+Buffer::Screenpos Buffer::findCursorInScreen() const {
+	if(screen.size()==0)return {-1,-1};
+	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;
+	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};
+}
+
 i64 numberWidth(i64 number){
 	if(number<0)return 1+numberWidth(-number);
 	if(number==0)return 1;
diff --git a/buffer.h b/buffer.h
index fd9b062..4c15703 100644
--- a/buffer.h
+++ b/buffer.h
@@ -34,9 +34,18 @@ class Buffer{
 	};
 	Cursorpos cursor={0,0};
 
+	struct Screenpos{
+		i64 y,x;
+	};
+
 	vector<ScreenLine> layoutLine(const string &line,i64 linenum,i64 width);
 	void performInitialLayout(i64 width,i64 height);
 	void renewLayout(i64 topLine,i64 topPart,i64 width,i64 height);
+	void relayoutScreen();
+
+	Screenpos findCursorInScreen() const;
+
+	void handleCommand(const Command &cmd);
 
 public:
 	string filename;