wip

src/native_functions.rs

@@ -3,7 +3,7 @@ use ordered_float::OrderedFloat;
 use std::{
     collections::HashMap,
     fs::File,
-    io::{BufReader, ErrorKind, Read},
+    io::{stdin, stdout, BufReader, ErrorKind, Read, Seek, SeekFrom, Write},
     rc::Rc,
     sync::RwLock,
     time::{SystemTime, UNIX_EPOCH},
@@ -53,7 +53,7 @@ impl Callable for ReadFile {
     }
 
     fn arity(&self) -> usize {
-        1
+        2
     }
 
     fn call(
@@ -61,18 +61,24 @@ impl Callable for ReadFile {
         _interpreter: &mut Interpreter,
         args: Vec<Value>,
     ) -> Result<Value, CallingError> {
-        if args.len() != self.arity() {
-            return Err(CallingError::ArgumentMismatch(self.arity(), args.len()));
-        }
-
-        let file_path = args
-            .first()
-            .ok_or(CallingError::CallFailed("arg not readable".into()))?;
+        let file_path = args.first().ok_or(CallingError::CallFailed(
+            "first arg must be file path".into(),
+        ))?;
         if let Value::String(file_path) = file_path {
             self.ensure_file_handle(file_path)?;
             let mut file_handles = FILE_HANDLES.write().unwrap();
             let reader = file_handles.get_mut(file_path).unwrap();
             let mut buffer = [0; 1];
+
+            let backwards = args.get(1).unwrap_or(&Value::Boolean(false));
+            if let Value::Boolean(backwards) = backwards {
+                if *backwards {
+                    reader
+                        .seek(SeekFrom::Current(-2))
+                        .map_err(|e| CallingError::CallFailed(e.to_string()))?;
+                }
+            }
+
             let character = match reader.read_exact(&mut buffer) {
                 Ok(_) => {
                     let character = buffer[0] as char;
@@ -143,9 +149,81 @@ impl Callable for Out {
     }
 }
 
+struct AsciiOut;
+impl Callable for AsciiOut {
+    fn name(&self) -> String {
+        "asciiOut".into()
+    }
+
+    fn arity(&self) -> usize {
+        1
+    }
+
+    fn call(&self, interpreter: &mut Interpreter, args: Vec<Value>) -> Result<Value, CallingError> {
+        if args.len() != self.arity() {
+            return Err(CallingError::ArgumentMismatch(self.arity(), args.len()));
+        }
+
+        let value = args
+            .first()
+            .ok_or(CallingError::CallFailed("arg not readable".into()))?;
+        if let Value::Number(value) = value {
+            let ascii = value.0 as u8 as char;
+            print!("{ascii}");
+
+            Ok(Value::Nil)
+        } else {
+            Err(CallingError::CallFailed(
+                "file_path arg must be a number".into(),
+            ))
+        }
+    }
+}
+
+struct PromptAscii;
+impl Callable for PromptAscii {
+    fn name(&self) -> String {
+        "prompt_ascii".into()
+    }
+
+    fn arity(&self) -> usize {
+        1
+    }
+
+    fn call(
+        &self,
+        _interpreter: &mut Interpreter,
+        args: Vec<Value>,
+    ) -> Result<Value, CallingError> {
+        if args.len() != self.arity() {
+            return Err(CallingError::ArgumentMismatch(self.arity(), args.len()));
+        }
+
+        let prompt = args
+            .first()
+            .ok_or(CallingError::CallFailed("arg not readable".into()))?;
+        if let Value::String(prompt) = prompt {
+            print!("{prompt} ");
+            stdout().flush();
+
+            let mut buffer = [0; 1];
+            stdin().read_exact(&mut buffer);
+
+            todo!()
+            // Ok(Value::Number(buffer[0] as char))
+        } else {
+            Err(CallingError::CallFailed("prompt must be a string".into()))
+        }
+    }
+}
+
 /// Return all native functions available to the Lox interpreter
 pub fn all() -> Vec<(String, Value)> {
     vec![
+        (
+            "asciiOut".into(),
+            Value::Callable((Rc::new(AsciiOut {}), CallableType::Function)),
+        ),
         (
             "clock".into(),
             Value::Callable((Rc::new(Clock {}), CallableType::Function)),
@@ -158,5 +236,9 @@ pub fn all() -> Vec<(String, Value)> {
             "read".into(),
             Value::Callable((Rc::new(ReadFile {}), CallableType::Function)),
         ),
+        (
+            "prompt".into(),
+            Value::Callable((Rc::new(PromptAscii {}), CallableType::Function)),
+        ),
     ]
 }