forked from AbleScript/ablescript
Added basic parsing
- Expressions - If, Functio
This commit is contained in:
ondra05
parent
d66874624b
commit
afee5fb82d
|
|
@ -5,7 +5,7 @@
|
|||
//!
|
||||
//! Expressions are just operations and they cannot be
|
||||
//! used as statements. Functions in AbleScript are in fact
|
||||
//! just plain subroutines and they do not return any value,
|
||||
//! just plain subroutines and they do not return any value,
|
||||
//! so their calls are statements.
|
||||
|
||||
use crate::variables::Value;
|
||||
|
|
@ -18,6 +18,12 @@ pub struct Iden {
|
|||
pub span: Span,
|
||||
}
|
||||
|
||||
impl Iden {
|
||||
pub fn new(iden: String, span: Span) -> Self {
|
||||
Self { iden, span }
|
||||
}
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
pub struct Block {
|
||||
pub block: Vec<Stmt>,
|
||||
|
|
|
|||
16
src/error.rs
16
src/error.rs
|
|
@ -1,6 +1,6 @@
|
|||
use std::ops::Range;
|
||||
|
||||
use crate::brian::InterpretError;
|
||||
use crate::{brian::InterpretError, lexer::Token};
|
||||
|
||||
#[derive(Debug, Clone)]
|
||||
pub struct Error {
|
||||
|
|
@ -11,7 +11,8 @@ pub struct Error {
|
|||
#[derive(Debug, Clone)]
|
||||
pub enum ErrorKind {
|
||||
SyntaxError(String),
|
||||
EndOfTokenStream,
|
||||
UnexpectedEof,
|
||||
UnexpectedToken(Token),
|
||||
InvalidIdentifier,
|
||||
UnknownVariable(String),
|
||||
MeloVariable(String),
|
||||
|
|
@ -19,4 +20,15 @@ pub enum ErrorKind {
|
|||
TopLevelBreak,
|
||||
ArithmeticError,
|
||||
BfInterpretError(InterpretError),
|
||||
MissingLhs,
|
||||
}
|
||||
|
||||
impl Error {
|
||||
pub fn new(kind: ErrorKind, span: Range<usize>) -> Self {
|
||||
Self { kind, span }
|
||||
}
|
||||
|
||||
pub fn unexpected_eof() -> Self {
|
||||
Self::new(ErrorKind::UnexpectedEof, 0..0)
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -6,10 +6,10 @@ use crate::variables::Abool;
|
|||
pub enum Token {
|
||||
// Symbols
|
||||
#[token("(")]
|
||||
LeftParenthesis,
|
||||
LeftParen,
|
||||
|
||||
#[token(")")]
|
||||
RightParenthesis,
|
||||
RightParen,
|
||||
|
||||
#[token("[")]
|
||||
LeftBracket,
|
||||
|
|
@ -184,8 +184,8 @@ mod tests {
|
|||
let expected = &[
|
||||
Functio,
|
||||
Identifier("test".to_owned()),
|
||||
LeftParenthesis,
|
||||
RightParenthesis,
|
||||
LeftParen,
|
||||
RightParen,
|
||||
LeftCurly,
|
||||
Variable,
|
||||
Identifier("a".to_owned()),
|
||||
|
|
|
|||
261
src/parser.rs
Normal file
261
src/parser.rs
Normal file
|
|
@ -0,0 +1,261 @@
|
|||
//! AbleScript Parser
|
||||
//!
|
||||
//! Type of this parser is recursive descent
|
||||
|
||||
use logos::{Lexer, Logos};
|
||||
|
||||
use crate::ast::*;
|
||||
use crate::error::{Error, ErrorKind};
|
||||
use crate::lexer::Token;
|
||||
use crate::variables::Value;
|
||||
|
||||
/// Parser structure which holds lexer and metadata
|
||||
///
|
||||
/// Make one using [`Parser::new`] function
|
||||
pub struct Parser<'source> {
|
||||
lexer: Lexer<'source, Token>,
|
||||
}
|
||||
|
||||
impl<'source> Parser<'source> {
|
||||
/// Create a new parser from source code
|
||||
pub fn new(source: &'source str) -> Self {
|
||||
Self {
|
||||
lexer: Token::lexer(source),
|
||||
}
|
||||
}
|
||||
|
||||
/// Start parsing tokens
|
||||
///
|
||||
/// Loops trough lexer, parses statements, returns AST
|
||||
pub fn init(&mut self) -> Result<Vec<Stmt>, Error> {
|
||||
let mut ast = vec![];
|
||||
while let Some(token) = self.lexer.next() {
|
||||
ast.push(self.parse(token)?);
|
||||
}
|
||||
Ok(ast)
|
||||
}
|
||||
|
||||
/// Parse a token
|
||||
///
|
||||
/// This function will route to corresponding flow functions
|
||||
/// which may advance the lexer iterator
|
||||
fn parse(&mut self, token: Token) -> Result<Stmt, Error> {
|
||||
let start = self.lexer.span().start;
|
||||
|
||||
match token {
|
||||
Token::If => Ok(Stmt::new(self.if_flow()?, start..self.lexer.span().end)),
|
||||
Token::Functio => Ok(Stmt::new(
|
||||
self.functio_flow()?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
t => Err(Error {
|
||||
kind: ErrorKind::UnexpectedToken(t),
|
||||
span: start..self.lexer.span().end,
|
||||
}),
|
||||
}
|
||||
}
|
||||
|
||||
/// Require next item to be equal with expected one
|
||||
fn require(&mut self, expected: Token) -> Result<(), Error> {
|
||||
match self.lexer.next() {
|
||||
Some(t) if t == expected => Ok(()),
|
||||
Some(t) => Err(Error::new(ErrorKind::UnexpectedToken(t), self.lexer.span())),
|
||||
None => Err(Error::unexpected_eof()),
|
||||
}
|
||||
}
|
||||
|
||||
/// Get an Identifier
|
||||
fn get_iden(&mut self) -> Result<Iden, Error> {
|
||||
match self.lexer.next().ok_or(Error::unexpected_eof())? {
|
||||
Token::Identifier(iden) => Ok(Iden {
|
||||
iden,
|
||||
span: self.lexer.span(),
|
||||
}),
|
||||
t => Err(Error::new(ErrorKind::UnexpectedToken(t), self.lexer.span())),
|
||||
}
|
||||
}
|
||||
|
||||
/// Parse an expression
|
||||
///
|
||||
/// AbleScript strongly separates expressions from statements.
|
||||
/// Expressions do not have any side effects and the are
|
||||
/// only mathematial and logical operations or values.
|
||||
fn parse_expr(&mut self, token: Token, buf: &mut Option<Expr>) -> Result<Expr, Error> {
|
||||
let start = self.lexer.span().start;
|
||||
|
||||
match token {
|
||||
// Values
|
||||
Token::Identifier(i) => Ok(Expr::new(
|
||||
ExprKind::Variable(i),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Abool(a) => Ok(Expr::new(
|
||||
ExprKind::Literal(Value::Abool(a)),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Bool(b) => Ok(Expr::new(
|
||||
ExprKind::Literal(Value::Bool(b)),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Integer(i) => Ok(Expr::new(
|
||||
ExprKind::Literal(Value::Int(i)),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::String(s) => Ok(Expr::new(
|
||||
ExprKind::Literal(Value::Str(s)),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Nul => Ok(Expr::new(
|
||||
ExprKind::Literal(Value::Nul),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
|
||||
// Operations
|
||||
Token::Plus => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Add, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Minus => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Subtract, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Star => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Multiply, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::FwdSlash => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Divide, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::EqualEqual => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Equal, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::NotEqual => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::NotEqual, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::And => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::And, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::Or => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Or, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::LessThan => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Less, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::GreaterThan => Ok(Expr::new(
|
||||
self.op_flow(BinOpKind::Greater, buf)?,
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
|
||||
Token::Not => Ok(Expr::new(
|
||||
{
|
||||
let next = self.lexer.next().ok_or(Error::unexpected_eof())?;
|
||||
ExprKind::Not(Box::new(self.parse_expr(next, buf)?))
|
||||
},
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
Token::LeftParen => self.expr_flow(Token::RightParen),
|
||||
t => Err(Error::new(
|
||||
ErrorKind::UnexpectedToken(t),
|
||||
start..self.lexer.span().end,
|
||||
)),
|
||||
}
|
||||
}
|
||||
|
||||
/// Flow for operators
|
||||
///
|
||||
/// Generates operation from LHS buffer and next expression as RHS
|
||||
///
|
||||
/// This is unaware of precedence, as AbleScript do not have it
|
||||
fn op_flow(&mut self, kind: BinOpKind, lhs: &mut Option<Expr>) -> Result<ExprKind, Error> {
|
||||
Ok(ExprKind::BinOp {
|
||||
lhs: Box::new(
|
||||
lhs.take()
|
||||
.ok_or(Error::new(ErrorKind::MissingLhs, self.lexer.span()))?,
|
||||
),
|
||||
rhs: {
|
||||
let next = self.lexer.next().ok_or(Error::unexpected_eof())?;
|
||||
Box::new(self.parse_expr(next, &mut None)?)
|
||||
},
|
||||
kind,
|
||||
})
|
||||
}
|
||||
|
||||
/// Parse expressions until terminate token
|
||||
fn expr_flow(&mut self, terminate: Token) -> Result<Expr, Error> {
|
||||
let mut buf = None;
|
||||
Ok(loop {
|
||||
match self.lexer.next().ok_or(Error::unexpected_eof())? {
|
||||
t if t == terminate => break buf.take().unwrap(),
|
||||
t => buf = Some(self.parse_expr(t, &mut buf)?),
|
||||
}
|
||||
})
|
||||
}
|
||||
|
||||
/// Parse a list of statements between curly braces
|
||||
fn parse_block(&mut self) -> Result<Block, Error> {
|
||||
self.require(Token::LeftCurly)?;
|
||||
let mut block = vec![];
|
||||
|
||||
loop {
|
||||
match self.lexer.next().ok_or(Error::unexpected_eof())? {
|
||||
Token::RightCurly => break,
|
||||
t => block.push(self.parse(t)?),
|
||||
}
|
||||
}
|
||||
Ok(Block { block })
|
||||
}
|
||||
|
||||
/// Parse If flow
|
||||
///
|
||||
/// Consists of condition and block, there is no else
|
||||
fn if_flow(&mut self) -> Result<StmtKind, Error> {
|
||||
self.require(Token::LeftParen)?;
|
||||
|
||||
let cond = self.expr_flow(Token::RightParen)?;
|
||||
|
||||
let body = self.parse_block()?;
|
||||
|
||||
Ok(StmtKind::If { cond, body })
|
||||
}
|
||||
|
||||
/// Parse functio flow
|
||||
///
|
||||
/// functio $iden (a, b, c) { ... }
|
||||
fn functio_flow(&mut self) -> Result<StmtKind, Error> {
|
||||
let iden = self.get_iden()?;
|
||||
|
||||
self.require(Token::LeftParen)?;
|
||||
|
||||
let mut args = vec![];
|
||||
loop {
|
||||
match self.lexer.next().ok_or(Error::unexpected_eof())? {
|
||||
Token::RightParen => break,
|
||||
Token::Identifier(i) => {
|
||||
args.push(Iden::new(i, self.lexer.span()));
|
||||
|
||||
match self.lexer.next().ok_or(Error::unexpected_eof())? {
|
||||
Token::Comma => continue,
|
||||
Token::RightParen => break,
|
||||
t => {
|
||||
return Err(Error::new(
|
||||
ErrorKind::UnexpectedToken(t),
|
||||
self.lexer.span(),
|
||||
))
|
||||
}
|
||||
}
|
||||
}
|
||||
t => return Err(Error::new(ErrorKind::UnexpectedToken(t), self.lexer.span())),
|
||||
}
|
||||
}
|
||||
|
||||
let body = self.parse_block()?;
|
||||
|
||||
Ok(StmtKind::Functio { iden, args, body })
|
||||
}
|
||||
}
|
||||
Loading…
Reference in a new issue