Don’t hard-code escape sequences

Instead of hard-coding VT100-compatible escape sequences, parse the
system terminfo database and read escape sequences from it. This is
both more flexible (it should work well on more terminals) and more
efficient (it won’t insert padding on terminals that don’t need it).

1 files changed, 74 insertions, 0 deletions

diff --git a/goldfishterm/simple.cc b/goldfishterm/simple.cc
new file mode 100644
index 0000000..9c4c9a9
--- /dev/null
+++ b/goldfishterm/simple.cc
@@ -0,0 +1,74 @@
+// Copyright 2021 Benjamin Barenblat
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+#include "goldfishterm/simple.h"
+
+#include <stdlib.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include <stdexcept>
+#include <vector>
+
+#include "goldfishterm/internal/emit.h"
+#include "goldfishterm/terminfo.h"
+#include "third_party/abseil/absl/strings/string_view.h"
+
+namespace goldfishterm {
+
+namespace {
+
+using ::goldfishterm_internal::InterpretStringCapability;
+using ::goldfishterm_internal::InterpretStringCapabilityInput;
+
+termios StdoutTermios() {
+  termios tty;
+  if (tcgetattr(STDOUT_FILENO, &tty) < 0) {
+    throw std::system_error(errno, std::system_category(), "tcgetattr");
+  }
+  return tty;
+}
+
+absl::string_view TerminalNameFromEnvironment() {
+  const char* name = getenv("TERM");
+  if (name == nullptr) {
+    throw std::runtime_error("TERM unset");
+  }
+  return name;
+}
+
+}  // namespace
+
+SimpleTerminalOutput::SimpleTerminalOutput()
+    : SimpleTerminalOutput(StdoutTermios()) {}
+
+SimpleTerminalOutput::SimpleTerminalOutput(const termios& tty)
+    : terminfo_(
+          TerminfoEntry::FromSystemDatabase(TerminalNameFromEnvironment())) {
+  baud_ = cfgetospeed(&tty);
+}
+
+void SimpleTerminalOutput::Emit(
+    StringCapability cap,
+    std::vector<goldfishterm_internal::StringCapabilityParameter> parameters) {
+  goldfishterm_internal::Emit(
+      InterpretStringCapability(
+          InterpretStringCapabilityInput(terminfo_, terminfo_.get(cap).value(),
+                                         std::move(parameters), /*baud=*/baud_,
+                                         /*lines_affected=*/1))
+          .terms,
+      std::cout);
+}
+
+}  // namespace goldfishterm