diff --git a/src/interpret.rs b/src/interpret.rs index b526317..493edeb 100644 --- a/src/interpret.rs +++ b/src/interpret.rs @@ -7,17 +7,18 @@ //! evaluate or execute any number of expressions or statements. #[deny(missing_docs)] -use std::collections::HashMap; use std::{ - convert::TryFrom, + collections::HashMap, io::{stdout, Write}, + ops::Range, process::exit, + usize, }; use rand::random; use crate::{ - ast::{Expr, Stmt, StmtKind}, + ast::{Expr, Iden, Stmt, StmtKind}, base_55, error::{Error, ErrorKind}, variables::{Functio, Value, Variable}, @@ -43,16 +44,16 @@ struct Scope { /// The reason a successful series of statements halted. enum HaltStatus { - /// The last statement in the list evaluated to this value. - Value(Value), + /// We ran out of statements to execute. + Finished, - /// A `break` statement occurred and was not caught by a `loop` - /// statement. - Break, + /// A `break` statement occurred at the given span, and was not + /// caught by a `loop` statement up to this point. + Break(Range), - /// A `hopback` statement occurred and was not caught by a `loop` - /// statement. - Hopback, + /// A `hopback` statement occurred at the given span, and was not + /// caught by a `loop` statement up to this point. + Hopback(Range), } impl ExecEnv { @@ -67,14 +68,14 @@ impl ExecEnv { /// Execute a set of Statements in their own stack frame. Return /// an error if one or more of the Stmts failed to evaluate, or if /// a `break` or `hopback` statement occurred at the top level. - pub fn eval_stmts(&mut self, stmts: &[Stmt]) -> Result { + pub fn eval_stmts(&mut self, stmts: &[Stmt]) -> Result<(), Error> { match self.eval_stmts_hs(stmts)? { - HaltStatus::Value(v) => Ok(v), - HaltStatus::Break | HaltStatus::Hopback => Err(Error { + HaltStatus::Finished => Ok(()), + HaltStatus::Break(span) | HaltStatus::Hopback(span) => Err(Error { // It's an error to issue a `break` outside of a // `loop` statement. kind: ErrorKind::TopLevelBreak, - span: 0..0, + span: span, }), } } @@ -88,10 +89,10 @@ impl ExecEnv { let init_depth = self.stack.len(); self.stack.push(Default::default()); - let mut final_result = Ok(HaltStatus::Value(Value::Nul)); + let mut final_result = Ok(HaltStatus::Finished); for stmt in stmts { final_result = self.eval_stmt(stmt); - if !matches!(final_result, Ok(HaltStatus::Value(_))) { + if !matches!(final_result, Ok(HaltStatus::Finished)) { break; } } @@ -115,8 +116,8 @@ impl ExecEnv { match kind { // Arithmetic operators. Add | Subtract | Multiply | Divide => { - let lhs = i32::try_from(lhs)?; - let rhs = i32::try_from(rhs)?; + let lhs = lhs.to_i32(&expr.span)?; + let rhs = rhs.to_i32(&expr.span)?; let res = match kind { Add => lhs.checked_add(rhs), @@ -134,8 +135,8 @@ impl ExecEnv { // Numeric comparisons. Less | Greater => { - let lhs = i32::try_from(lhs)?; - let rhs = i32::try_from(rhs)?; + let lhs = lhs.to_i32(&expr.span)?; + let rhs = rhs.to_i32(&expr.span)?; let res = match kind { Less => lhs < rhs, @@ -157,8 +158,8 @@ impl ExecEnv { // Logical connectives. And | Or => { - let lhs = bool::from(lhs); - let rhs = bool::from(rhs); + let lhs = lhs.to_bool(); + let rhs = rhs.to_bool(); let res = match kind { And => lhs && rhs, Or => lhs || rhs, @@ -168,9 +169,15 @@ impl ExecEnv { } } } - Not(expr) => Bool(!bool::from(self.eval_expr(&expr)?)), + Not(expr) => Bool(!self.eval_expr(&expr)?.to_bool()), Literal(value) => value.clone(), - Variable(name) => self.get_var(&name)?, + + // TODO: not too happy with constructing an artificial + // Iden here. + Variable(name) => self.get_var(&Iden { + iden: name.to_owned(), + span: expr.span.clone(), + })?, }) } @@ -203,12 +210,12 @@ impl ExecEnv { // ); // } StmtKind::If { cond, body } => { - if self.eval_expr(cond)?.into() { + if self.eval_expr(cond)?.to_bool() { return self.eval_stmts_hs(&body.block); } } StmtKind::Call { iden, args } => { - let func = self.get_var(&iden.iden)?; + let func = self.get_var(&iden)?; match func { Value::Functio(func) => { match func { @@ -249,9 +256,9 @@ impl ExecEnv { StmtKind::Loop { body } => loop { let res = self.eval_stmts_hs(&body.block)?; match res { - HaltStatus::Value(_) => {} - HaltStatus::Break => break, - HaltStatus::Hopback => continue, + HaltStatus::Finished => {} + HaltStatus::Break(_) => break, + HaltStatus::Hopback(_) => continue, } }, // This is missing as well. ~~Alex @@ -259,13 +266,13 @@ impl ExecEnv { // self.get_var_mut(&iden.0)?.value = self.eval_expr(value)?; // } StmtKind::Break => { - return Ok(HaltStatus::Break); + return Ok(HaltStatus::Break(stmt.span.clone())); } StmtKind::HopBack => { - return Ok(HaltStatus::Hopback); + return Ok(HaltStatus::Hopback(stmt.span.clone())); } StmtKind::Melo(iden) => { - self.get_var_mut(&iden.iden)?.melo = true; + self.get_var_mut(&iden)?.melo = true; } StmtKind::Rlyeh => { // Maybe print a creepy error message or something @@ -274,14 +281,14 @@ impl ExecEnv { } } - Ok(HaltStatus::Value(Value::Nul)) + Ok(HaltStatus::Finished) } /// Get the value of a variable. Throw an error if the variable is /// inaccessible or banned. - fn get_var(&self, name: &str) -> Result { + fn get_var(&self, name: &Iden) -> Result { // One-letter names are reserved as base55 numbers. - let mut chars = name.chars(); + let mut chars = name.iden.chars(); if let (Some(first), None) = (chars.next(), chars.next()) { return Ok(Value::Int(base_55::char2num(first))); } @@ -292,51 +299,49 @@ impl ExecEnv { .stack .iter() .rev() - .find_map(|scope| scope.variables.get(name)) + .find_map(|scope| scope.variables.get(&name.iden)) { Some(var) => { if !var.melo { Ok(var.value.clone()) } else { Err(Error { - kind: ErrorKind::MeloVariable(name.to_owned()), - // TODO: figure out some way to avoid this - // 0..0 dumbness - span: 0..0, + kind: ErrorKind::MeloVariable(name.iden.to_owned()), + span: name.span.clone(), }) } } None => Err(Error { - kind: ErrorKind::UnknownVariable(name.to_owned()), - span: 0..0, + kind: ErrorKind::UnknownVariable(name.iden.to_owned()), + span: name.span.clone(), }), } } /// Get a mutable reference to a variable. Throw an error if the /// variable is inaccessible or banned. - fn get_var_mut(&mut self, name: &str) -> Result<&mut Variable, Error> { + fn get_var_mut(&mut self, name: &Iden) -> Result<&mut Variable, Error> { // This function has a lot of duplicated code with `get_var`, // which I feel like is a bad sign... match self .stack .iter_mut() .rev() - .find_map(|scope| scope.variables.get_mut(name)) + .find_map(|scope| scope.variables.get_mut(&name.iden)) { Some(var) => { if !var.melo { Ok(var) } else { Err(Error { - kind: ErrorKind::MeloVariable(name.to_owned()), - span: 0..0, + kind: ErrorKind::MeloVariable(name.iden.to_owned()), + span: name.span.clone(), }) } } None => Err(Error { - kind: ErrorKind::UnknownVariable(name.to_owned()), - span: 0..0, + kind: ErrorKind::UnknownVariable(name.iden.to_owned()), + span: name.span.clone(), }), } } @@ -367,15 +372,15 @@ mod tests { kind: ExprKind::BinOp { lhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(2)), - span: 0..0, + span: 1..1, }), rhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(2)), - span: 0..0, + span: 1..1, }), kind: crate::ast::BinOpKind::Add, }, - span: 0..0 + span: 1..1 }) .unwrap(), Value::Int(4) @@ -392,15 +397,15 @@ mod tests { kind: ExprKind::BinOp { lhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(2)), - span: 0..0, + span: 1..1, }), rhs: Box::new(Expr { kind: ExprKind::Literal(Value::Bool(true)), - span: 0..0, + span: 1..1, }), kind: crate::ast::BinOpKind::Add, }, - span: 0..0 + span: 1..1 }), Err(Error { kind: ErrorKind::TypeError(_), @@ -419,15 +424,15 @@ mod tests { kind: ExprKind::BinOp { lhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(i32::MAX)), - span: 0..0, + span: 1..1, }), rhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(1)), - span: 0..0, + span: 1..1, }), kind: crate::ast::BinOpKind::Add, }, - span: 0..0 + span: 1..1 }), Err(Error { kind: ErrorKind::ArithmeticError, @@ -441,15 +446,15 @@ mod tests { kind: ExprKind::BinOp { lhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(1)), - span: 0..0, + span: 1..1, }), rhs: Box::new(Expr { kind: ExprKind::Literal(Value::Int(0)), - span: 0..0, + span: 1..1, }), kind: crate::ast::BinOpKind::Divide, }, - span: 0..0 + span: 1..1 }), Err(Error { kind: ErrorKind::ArithmeticError, @@ -467,7 +472,7 @@ mod tests { // We can assume there won't be any syntax errors in the // interpreter tests. let ast = parser.init().unwrap(); - env.eval_stmts(&ast) + env.eval_stmts(&ast).map(|()| Value::Nul) } #[test] diff --git a/src/variables.rs b/src/variables.rs index d8f029d..fe8d358 100644 --- a/src/variables.rs +++ b/src/variables.rs @@ -1,4 +1,4 @@ -use std::{convert::TryFrom, fmt::Display, io::Write}; +use std::{fmt::Display, io::Write, ops::Range}; use rand::Rng; @@ -51,7 +51,7 @@ pub enum Value { } impl Value { - /// Writes an AbleScript value to a Brainfuck input stream. This + /// Write an AbleScript value to a Brainfuck input stream. This /// should generally only be called on `Write`rs that cannot fail, /// e.g., `Vec`, because any IO errors will cause a panic. /// @@ -105,6 +105,38 @@ impl Value { } .expect("Failed to write to Brainfuck input"); } + + /// Attempt to coerce a Value to an integer. If the conversion + /// fails, the generated error message is associated with the + /// given span. + pub fn to_i32(self, span: &Range) -> Result { + match self { + Value::Int(i) => Ok(i), + _ => Err(Error { + kind: ErrorKind::TypeError(format!("Expected int, got {}", self)), + span: span.clone(), + }), + } + } + + /// Coerce a Value to a boolean. The conversion cannot fail. + pub fn to_bool(self) -> bool { + match self { + // Booleans and abooleans have a trivial conversion. + Value::Bool(b) => b, + Value::Abool(b) => b.into(), + // The empty string is falsey, other strings are truthy. + Value::Str(s) => s.len() != 0, + // 0 is falsey, nonzero is truthy. + Value::Int(x) => x != 0, + // Functios are always truthy. + Value::Functio(_) => true, + // And nul is truthy as a symbol of the fact that the + // deep, fundamental truth of this world is nothing but + // the eternal void. + Value::Nul => true, + } + } } impl Display for Value { @@ -134,48 +166,6 @@ impl Display for Value { } } -impl TryFrom for i32 { - type Error = Error; - - fn try_from(value: Value) -> Result { - match value { - Value::Int(i) => Ok(i), - _ => Err(Error { - kind: ErrorKind::TypeError(format!("Expected int, got {}", value)), - // TODO: either add some kind of metadata to `Value` - // so we can tell where the value came from and assign - // this `position` correctly, or re-write the - // `error::Error` struct so we can omit the `position` - // when using some error kinds. - span: 0..0, - }), - } - } -} - -// Coercions from a value to a boolean always succeed, so every value -// can be used in an `if` statement. C does things that way, so how -// could it possibly be a bad idea? -impl From for bool { - fn from(value: Value) -> Self { - match value { - // Booleans and abooleans have a trivial conversion. - Value::Bool(b) => b, - Value::Abool(b) => b.into(), - // The empty string is falsey, other strings are truthy. - Value::Str(s) => s.len() != 0, - // 0 is falsey, nonzero is truthy. - Value::Int(x) => x != 0, - // Functios are always truthy. - Value::Functio(_) => true, - // And nul is truthy as a symbol of the fact that the - // deep, fundamental truth of this world is nothing but - // the eternal void. - Value::Nul => true, - } - } -} - #[derive(Debug)] pub struct Variable { pub melo: bool,