LibLine: Parse CSI parameters and immediates

No behavior change, but it makes it easy to handle
page up and page down if we wanted to make them do something
in libline.

Libraries/LibLine/Editor.cpp

@@ -631,6 +631,11 @@ void Editor::handle_read_event()
     Utf8View input_view { StringView { m_incomplete_data.data(), valid_bytes } };
     size_t consumed_code_points = 0;
 
+    Vector<u8, 4> csi_parameter_bytes;
+    Vector<unsigned, 4> csi_parameters;
+    Vector<u8> csi_intermediate_bytes;
+    u8 csi_final;
+
     for (auto code_point : input_view) {
         if (m_finish)
             break;
@@ -644,7 +649,7 @@ void Editor::handle_read_event()
         case InputState::GotEscape:
             switch (code_point) {
             case '[':
-                m_state = InputState::GotEscapeFollowedByLeftBracket;
+                m_state = InputState::CSIExpectParameter;
                 continue;
             default: {
                 m_state = InputState::Free;
@@ -658,29 +663,55 @@ void Editor::handle_read_event()
                 continue;
             }
             }
-        case InputState::GotEscapeFollowedByLeftBracket:
-            if (code_point == 'O') {
+        case InputState::CSIExpectParameter:
+            if (code_point >= 0x30 && code_point <= 0x3f) { // '0123456789:;<=>?'
+                csi_parameter_bytes.append(code_point);
+                continue;
+            }
+            m_state = InputState::CSIExpectIntermediate;
+            [[fallthrough]];
+        case InputState::CSIExpectIntermediate:
+            if (code_point >= 0x20 && code_point <= 0x2f) { // ' !"#$%&\'()*+,-./'
+                csi_intermediate_bytes.append(code_point);
+                continue;
+            }
+            m_state = InputState::CSIExpectFinal;
+            [[fallthrough]];
+        case InputState::CSIExpectFinal:
+            m_state = InputState::Free;
+            if (!(code_point >= 0x40 && code_point <= 0x7f)) {
+                dbgprintf("LibLine: Invalid CSI: %02x (%c)\r\n", code_point, code_point);
+                ctrl_held = false;
+                continue;
+            }
+            csi_final = code_point;
+
+            for (auto& parameter : String::copy(csi_parameter_bytes).split(';')) {
+                if (auto value = parameter.to_uint(); value.has_value())
+                    csi_parameters.append(value.value());
+                else
+                    csi_parameters.append(0);
+            }
+
+            if (csi_final == 'O') {
                 // mod_ctrl
                 ctrl_held = true;
                 continue;
             }
-            if (code_point == 'Z') {
+            if (csi_final == 'Z') {
                 // 'reverse tab'
                 reverse_tab = true;
-                m_state = InputState::Free;
                 ctrl_held = false;
                 break;
             }
             cleanup_suggestions();
-            switch (code_point) {
+            switch (csi_final) {
             case 'A': // ^[[A: arrow up
                 search_backwards();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             case 'B': // ^[[B: arrow down
                 search_forwards();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             case 'D': // ^[[D: arrow left
@@ -688,7 +719,6 @@ void Editor::handle_read_event()
                     cursor_left_word();
                 else
                     cursor_left_character();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             case 'C': // ^[[C: arrow right
@@ -696,35 +726,34 @@ void Editor::handle_read_event()
                     cursor_right_word();
                 else
                     cursor_right_character();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             case 'H': // ^[[H: home
                 go_home();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             case 'F': // ^[[F: end
                 go_end();
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
-            case '3': // ^[[3~: delete
-                erase_character_forwards();
-                m_search_offset = 0;
-                m_state = InputState::ExpectTerminator;
+            case '~':
+                if (csi_parameters.size() == 1 && csi_parameters[0] == 3) { // ^[[3~: delete
+                    erase_character_forwards();
+                    m_search_offset = 0;
+                    ctrl_held = false;
+                    continue;
+                }
+                // ^[[5~: page up
+                // ^[[6~: page down
+                dbgprintf("LibLine: Unhandled '~'\r\n");
                 ctrl_held = false;
                 continue;
             default:
                 dbgprintf("LibLine: Unhandled final: %02x (%c)\r\n", code_point, code_point);
-                m_state = InputState::Free;
                 ctrl_held = false;
                 continue;
             }
             break;
-        case InputState::ExpectTerminator:
-            m_state = InputState::Free;
-            continue;
         case InputState::Free:
             if (code_point == 27) {
                 m_state = InputState::GotEscape;

Libraries/LibLine/Editor.h

@@ -471,8 +471,9 @@ private:
     enum class InputState {
         Free,
         GotEscape,
-        GotEscapeFollowedByLeftBracket,
-        ExpectTerminator,
+        CSIExpectParameter,
+        CSIExpectIntermediate,
+        CSIExpectFinal,
     };
     InputState m_state { InputState::Free };