LSP: Beginning a language server (#511)

Right now all it does is listen to stdin, and write the messages it
receives to a log file. But, quite a few standard library functions
needed to be added to get to this point.

projects/lsp/.gitignore

@@ -0,0 +1,2 @@
+.DS_Store
+log.txt

projects/lsp/src/main.abra

@@ -0,0 +1,18 @@
+import "process" as process
+import "fs" as fs
+
+val cwd = fs.getCurrentWorkingDirectory()
+val logFilePath = "$cwd/log.txt"
+val logFile = match fs.createFile(logFilePath, fs.AccessMode.WriteOnly) {
+  Ok(v) => v
+  Err(e) => {
+    println(e)
+    process.exit(1)
+  }
+}
+
+val stdin = process.stdin()
+
+while stdin.readAsString() |str| {
+  logFile.writeln(str)
+}

projects/std/src/fs.abra

@@ -9,7 +9,7 @@ export enum FileIOError {
 }
 
 export func readFile(path: String): Result<String, FileIOError> {
-  val fd = libc.open(path._buffer, libc.O_RDONLY)
+  val fd = libc.open(path._buffer, libc.O_RDONLY, 0)
   if fd == -1 {
     val errMsg = _strerror(libc.errno())
     return Err(error: FileIOError.CouldNotOpen(message: errMsg))
@@ -42,6 +42,12 @@ export enum AccessMode {
   ReadOnly
   WriteOnly
   ReadWrite
+
+  func _toUnderlying(self): Int = match self {
+    AccessMode.ReadOnly => libc.O_RDONLY
+    AccessMode.WriteOnly => libc.O_WRONLY
+    AccessMode.ReadWrite => libc.O_RDWR
+  }
 }
 
 export type File {
@@ -69,12 +75,21 @@ export type File {
 }
 
 export func openFile(path: String, accessMode: AccessMode): Result<File, FileIOError> {
-  val oflag = match accessMode {
-    AccessMode.ReadOnly => libc.O_RDONLY
-    AccessMode.WriteOnly => libc.O_WRONLY
-    AccessMode.ReadWrite => libc.O_RDWR
+  val oflag = accessMode._toUnderlying()
+  val fd = libc.open(path._buffer, oflag, 0)
+  if fd == -1 {
+    val errMsg = _strerror(libc.errno())
+    return Err(error: FileIOError.CouldNotOpen(message: errMsg))
   }
-  val fd = libc.open(path._buffer, oflag)
+
+  Ok(File(_fd: fd, accessMode: accessMode))
+}
+
+export func createFile(path: String, accessMode: AccessMode): Result<File, FileIOError> {
+  var oflag = accessMode._toUnderlying() || libc.O_CREAT
+
+  val mode = 420 // 420 is 0644, but octal numbers aren't supported yet...
+  val fd = libc.open(path._buffer, oflag, mode)
   if fd == -1 {
     val errMsg = _strerror(libc.errno())
     return Err(error: FileIOError.CouldNotOpen(message: errMsg))

projects/std/src/libc.abra

@@ -12,9 +12,10 @@ export func strerror(errno: Int): Pointer<Byte>
 export val O_RDONLY = 0
 export val O_WRONLY = 1
 export val O_RDWR   = 2
+export val O_CREAT  = 512
 
 @CBinding("open")
-export func open(pathname: Pointer<Byte>, flags: Int): Int
+export func open(pathname: Pointer<Byte>, flags: Int, mode: Int): Int
 
 @CBinding("close")
 export func close(fd: Int): Int
@@ -29,6 +30,9 @@ export func lseek(fd: Int, offset: Int, whence: Int): Int
 @CBinding("read")
 export func read(fd: Int, buf: Pointer<Byte>, count: Int): Int
 
+@CBinding("stat")
+export func stat(pathname: Pointer<Byte>, statbuf: Pointer<Byte>): Int
+
 export val STDIN_FILENO  = 0
 export val STDOUT_FILENO = 1
 export val STDERR_FILENO = 2

projects/std/src/process.abra

@@ -201,3 +201,25 @@ func getFunctionNames(): String[] {
   _functionNames = Some(functionNames)
   functionNames
 }
+
+type Stdin {
+  _buf: Pointer<Byte> = Pointer.malloc(1024)
+
+  func readAsString(self): String? {
+    var nread = libc.read(libc.STDIN_FILENO, self._buf, 1024)
+    if nread == 0 return None
+
+    val str = String.withLength(nread)
+    str._buffer.copyFrom(self._buf, nread)
+    return Some(str)
+  }
+}
+
+var _stdin: Stdin? = None
+export func stdin(): Stdin {
+  if _stdin |stdin| return stdin
+
+  val stdin = Stdin()
+  _stdin = Some(stdin)
+  stdin
+}