SeraphScript/src/parsing/parser/mod.rs

pub mod parsed_statement;
pub mod parsed_type_modifier;
#[cfg(test)]
mod parser_tests;

use super::lexer::lex_tokens::{LexToken, TokenType};
use crate::logger::messages::Message;
use crate::logger::messages::Message::UnexpectedToken;
use crate::modifiers::{FieldModifier, TypeModifier};
use crate::parsing::parser::parsed_type_modifier::ParsedTypeModifier;
use crate::span::Span;
use enumflags2::BitFlags;
use parsed_statement::ParsedStatement;

struct ParseReader<'a> {
    tokens: &'a Vec<LexToken>,
    position: usize,
    peek_distance: usize,
}

impl<'a> ParseReader<'a> {
    pub fn peek(&mut self) -> &LexToken {
        let t = self.tokens.get(self.position + self.peek_distance);
        self.peek_distance += 1;
        match t {
            None => self.tokens.last().unwrap(),
            Some(v) => {
                if v.token_type == TokenType::WhiteSpace {
                    self.peek()
                } else {
                    v
                }
            }
        }
    }

    pub fn next(&mut self) -> &LexToken {
        let t = self.tokens.get(self.position);
        self.position += 1;
        self.peek_distance = 0;
        match t {
            None => self.tokens.last().unwrap(),
            Some(v) => {
                if v.token_type == TokenType::WhiteSpace {
                    self.next()
                } else {
                    v
                }
            }
        }
    }

    pub fn move_to_peek(&mut self) {
        self.position += self.peek_distance;
        self.peek_distance = 0;
    }

    pub fn consume(
        &mut self,
        expected: TokenType,
        log: &mut dyn FnMut(Message, Span),
    ) -> &LexToken {
        let n = self.next();
        if n.token_type != expected {
            log(
                Message::UnexpectedToken {
                    expected: vec![expected],
                    found: n.token_type.clone(),
                },
                n.span,
            );
        }
        n
    }

    #[inline(always)]
    pub fn reset_peek(&mut self) {
        self.peek_distance = 0;
    }

    pub fn create_inner(&self) -> ParseReader<'a> {
        ParseReader {
            tokens: self.tokens,
            position: self.position,
            peek_distance: self.peek_distance,
        }
    }

    pub fn set_from_inner(&mut self, inner: &ParseReader) {
        self.position = inner.position;
        self.peek_distance = inner.peek_distance;
    }
}

pub fn parse(tokens: Vec<LexToken>, log: &mut dyn FnMut(Message, Span)) -> Box<ParsedStatement> {
    assert_ne!(tokens.len(), 0);
    let mut reader = ParseReader {
        tokens: &tokens,
        position: 0,
        peek_distance: 0,
    };
    parse_script(&mut reader, log)
}

fn parse_script(
    reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Box<ParsedStatement> {
    let mut vec: Vec<ParsedStatement> = Vec::new();
    loop {
        let n = reader.peek();
        let token_type = n.token_type.clone();
        let span = n.span;
        match token_type {
            TokenType::NamespaceKeyword => {
                vec.push(*parse_namespace(reader, log));
            }
            TokenType::InterfaceKeyword => vec.push(*parse_interface(reader, log).unwrap()),
            TokenType::EndOfFile => break,
            TokenType::CloseCurlyBracket => break,
            _ => {
                if let Some(s) = parse_interface(reader, log) {
                    vec.push(*s);
                } else {
                    log(
                        UnexpectedToken {
                            expected: vec![TokenType::NamespaceKeyword],
                            found: token_type,
                        },
                        span,
                    );
                    reader.next();
                }
            }
        }
    }

    Box::new(ParsedStatement::Script { statements: vec })
}

fn parse_identifier(
    reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Option<String> {
    let identifier_token = reader.next();
    let s: String;
    match &identifier_token.token_type {
        TokenType::Identifier(i) => {
            s = i.to_string();
        }
        _ => {
            log(
                Message::UnexpectedToken {
                    found: identifier_token.token_type.clone(),
                    expected: vec![TokenType::Identifier(String::new())],
                },
                identifier_token.span,
            );
            return None;
        }
    }
    Some(s)
}

fn parse_namespace(
    reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Box<ParsedStatement> {
    reader.next(); // Consume namespace
    let identifier = parse_identifier(reader, log);
    if identifier.is_none() {
        return Box::new(ParsedStatement::Invalid);
    }
    reader.consume(TokenType::OpenCurlyBracket, log);
    let script = parse_script(reader, log);
    reader.consume(TokenType::CloseCurlyBracket, log);
    Box::new(ParsedStatement::Namespace {
        identifier: identifier.unwrap(),
        script,
    })
}

fn parse_interface(
    reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Option<Box<ParsedStatement>> {
    let mut type_mod: BitFlags<TypeModifier> = BitFlags::empty();
    let identifier: Option<String>;
    let mut has_interface_keyword = false;
    reader.reset_peek();
    loop {
        match &reader.peek().token_type {
            TokenType::ExternalKeyword => type_mod |= TypeModifier::External,
            TokenType::SharedKeyword => type_mod |= TypeModifier::Shared,
            TokenType::Identifier(s) => {
                identifier = Some(s.clone());
                break;
            }
            TokenType::InterfaceKeyword => {
                has_interface_keyword = true;
            }
            _ => {
                return None;
            }
        };
    }
    if !has_interface_keyword {
        return None;
    }
    reader.move_to_peek();
    let mut statements: Vec<ParsedStatement> = Vec::new();
    let mut inherits: Vec<String> = Vec::new();
    loop {
        let t = reader.peek();
        match t.token_type {
            TokenType::Semicolon => {
                reader.next();
                if identifier.is_none() {
                    return Some(Box::new(ParsedStatement::Invalid));
                }
                return Some(Box::new(ParsedStatement::Interface {
                    type_mod,
                    identifier: identifier.unwrap(),
                    inherits,
                    statements,
                }));
            }
            TokenType::Colon | TokenType::OpenCurlyBracket => break,
            TokenType::EndOfFile => {
                log(
                    Message::UnexpectedToken {
                        found: t.token_type.clone(),
                        expected: vec![
                            TokenType::Semicolon,
                            TokenType::Colon,
                            TokenType::OpenCurlyBracket,
                        ],
                    },
                    t.span,
                );
                return Some(Box::new(ParsedStatement::Invalid));
            }
            _ => {
                log(
                    Message::UnexpectedToken {
                        found: t.token_type.clone(),
                        expected: vec![
                            TokenType::Semicolon,
                            TokenType::Colon,
                            TokenType::OpenCurlyBracket,
                        ],
                    },
                    t.span,
                );
            }
        }
    }
    reader.reset_peek();
    if reader.peek().token_type == TokenType::Colon {
        reader.next();
        loop {
            let inherit_identifier = parse_identifier(reader, log);
            if inherit_identifier.is_none() {
                continue;
            }
            inherits.push(inherit_identifier.unwrap());
            if reader.peek().token_type != TokenType::Comma {
                break;
            }
            reader.next();
        }
    }
    reader.consume(TokenType::OpenCurlyBracket, log);
    // TODO: parse interfacemethod
    loop {
        if reader.peek().token_type == TokenType::CloseCurlyBracket {
            break;
        }
        let prop = parse_virtprop(reader, log);
        if prop.is_none() {
            break;
        }
        statements.push(*prop.unwrap());
    }

    reader.consume(TokenType::CloseCurlyBracket, log);
    reader.move_to_peek();
    if identifier.is_none() {
        return Some(Box::new(ParsedStatement::Invalid));
    }

    Some(Box::new(ParsedStatement::Interface {
        type_mod,
        identifier: identifier.unwrap(),
        inherits,
        statements,
    }))
}

fn parse_statblock(
    _outer_reader: &mut ParseReader,
    _log: &mut dyn FnMut(Message, Span),
) -> Option<Box<ParsedStatement>> {
    unimplemented!();
}

fn parse_virtprop(
    outer_reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Option<Box<ParsedStatement>> {
    let mut reader = outer_reader.create_inner();
    let mut field_mod: BitFlags<FieldModifier> = BitFlags::empty();
    let property_type: Option<Box<ParsedStatement>>;
    loop {
        let t = reader.peek();
        match t.token_type {
            TokenType::PrivateKeyword => {
                field_mod |= FieldModifier::Private;
                reader.next();
            }
            TokenType::ProtectedKeyword => {
                field_mod |= FieldModifier::Protected;
                reader.next();
            }
            _ => {
                property_type = parse_type(&mut reader, log);
                property_type.as_ref()?;
                break;
            }
        }
    }
    let mut is_handle = false;
    if reader.peek().token_type == TokenType::Ampersand {
        reader.next();
        is_handle = true;
    }
    let identifier = parse_identifier(&mut reader, log);
    identifier.as_ref()?;
    let next = reader.next();
    if next.token_type != TokenType::OpenCurlyBracket {
        return None;
    }

    let mut has_get = false;
    let mut is_get_const = false;
    let mut get_statement: Option<Box<ParsedStatement>> = None;

    let mut has_set = false;
    let mut is_set_const = false;
    let mut set_statement: Option<Box<ParsedStatement>> = None;
    let start_span = next.span;

    loop {
        let next = reader.peek();
        match next.token_type {
            TokenType::GetKeyword => {
                reader.next();
                has_get = true;
                let mut peek = reader.peek();
                if peek.token_type == TokenType::ConstKeyword {
                    reader.next();
                    is_get_const = true;
                    peek = reader.peek();
                }
                if peek.token_type != TokenType::Semicolon {
                    get_statement = parse_statblock(&mut reader, log);
                } else {
                    reader.next();
                }
            }
            TokenType::SetKeyword => {
                reader.next();
                has_set = true;
                let mut peek = reader.peek();
                if peek.token_type == TokenType::ConstKeyword {
                    reader.next();
                    is_set_const = true;
                    peek = reader.peek();
                }
                if peek.token_type != TokenType::Semicolon {
                    set_statement = parse_statblock(&mut reader, log);
                } else {
                    reader.next();
                }
            }
            _ => break,
        }
    }

    let next = reader.next();
    if next.token_type != TokenType::CloseCurlyBracket {
        return None;
    }
    if !has_get && !has_set {
        log(
            Message::EmptyProperty,
            Span {
                start: start_span.start,
                end: next.span.end,
            },
        )
    }

    outer_reader.set_from_inner(&reader);
    Some(Box::new(ParsedStatement::VirtProp {
        field_mod,
        property_type: property_type.unwrap(),
        identifier: identifier.unwrap(),
        is_handle,
        has_get,
        is_get_const,
        get_statement,
        has_set,
        is_set_const,
        set_statement,
    }))
}

fn parse_type(
    reader: &mut ParseReader,
    log: &mut dyn FnMut(Message, Span),
) -> Option<Box<ParsedStatement>> {
    let f = reader.peek();
    let mut is_const = false;
    if f.token_type == TokenType::ConstKeyword {
        reader.next();
        is_const = true;
    }
    let scope = parse_scope(reader, log);
    let identifier = parse_identifier(reader, log);
    // if none, we already logged an error. Return None.
    identifier.as_ref()?;

    // TODO: Generics

    let mut modifiers: Vec<ParsedTypeModifier> = Vec::new();
    loop {
        let n = reader.peek();
        match n.token_type {
            TokenType::OpenBlockBracket => {
                reader.next();
                reader.consume(TokenType::CloseBlockBracket, log);
                modifiers.push(ParsedTypeModifier::Array);
            }
            TokenType::Ampersand => {
                reader.next();
                if reader.peek().token_type == TokenType::ConstKeyword {
                    reader.next();
                    modifiers.push(ParsedTypeModifier::ConstHandle);
                } else {
                    modifiers.push(ParsedTypeModifier::Handle);
                }
            }
            _ => break,
        }
    }

    Some(Box::new(ParsedStatement::Type {
        is_const,
        scope,
        identifier: identifier.unwrap(),
        modifiers,
    }))
}

fn parse_scope(
    outer_reader: &mut ParseReader,
    _log: &mut dyn FnMut(Message, Span),
) -> Option<Box<ParsedStatement>> {
    let mut reader = outer_reader.create_inner();
    let is_global = reader.peek().token_type == TokenType::ColonColon;
    if is_global {
        reader.next();
    }
    let mut scope: Vec<String> = Vec::new();
    loop {
        let n = reader.peek();
        if let TokenType::Identifier(s) = &n.token_type {
            let identifier = s.to_string();
            if reader.peek().token_type == TokenType::ColonColon {
                reader.next();
                reader.next();
                scope.push(identifier);
            } else {
                break;
            }
        } else {
            break;
        }
    }
    // TODO: generics
    if !is_global && scope.is_empty() {
        None
    } else {
        outer_reader.set_from_inner(&reader);
        Some(Box::new(ParsedStatement::Scope {
            is_global,
            scope,
            generic_types: None,
        }))
    }
}