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/**
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* Copyright 2020 Garrit Franke
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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use super::node_type::Statement;
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use super::node_type::*;
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use super::parser::Parser;
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use crate::lexer::Keyword;
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use crate::lexer::{TokenKind, Value};
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use std::convert::TryFrom;
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impl Parser {
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pub(super) fn parse_program(&mut self) -> Result<Program, String> {
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let mut functions = Vec::new();
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let globals = Vec::new();
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while self.has_more() {
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functions.push(self.parse_function()?)
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}
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Ok(Program {
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func: functions,
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globals: globals,
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})
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}
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fn parse_block(&mut self) -> Result<Statement, String> {
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self.match_token(TokenKind::CurlyBracesOpen)?;
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let mut statements = vec![];
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let mut scope = vec![];
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// Parse statements until a curly brace is encountered
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while let Err(_) = self.peek_token(TokenKind::CurlyBracesClose) {
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let statement = self.parse_statement()?;
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// If the current statement is a variable declaration,
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// let the scope know
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if let Statement::Declare(var, _) = &statement {
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// TODO: Not sure if we should clone here
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scope.push(var.to_owned());
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}
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statements.push(statement);
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}
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self.match_token(TokenKind::CurlyBracesClose)?;
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Ok(Statement::Block(statements, scope))
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}
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fn parse_function(&mut self) -> Result<Function, String> {
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self.match_keyword(Keyword::Function)?;
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let name = self.match_identifier()?;
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self.match_token(TokenKind::BraceOpen)?;
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let arguments: Vec<Variable> = match self.peek()? {
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t if t.kind == TokenKind::BraceClose => Vec::new(),
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_ => self.parse_arguments()?,
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};
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self.match_token(TokenKind::BraceClose)?;
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let ty = match self.peek()?.kind {
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TokenKind::Colon => Some(self.parse_type()?),
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_ => None,
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};
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let body = self.parse_block()?;
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Ok(Function {
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name: name,
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arguments: arguments,
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body: body,
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ret_type: ty,
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})
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}
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fn parse_arguments(&mut self) -> Result<Vec<Variable>, String> {
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let mut args = Vec::new();
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while let Err(_) = self.peek_token(TokenKind::BraceClose) {
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let next = self.next()?;
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match next.kind {
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TokenKind::Comma => {
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continue;
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}
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TokenKind::Identifier(name) => {
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args.push(Variable {
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name: name,
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ty: Some(self.parse_type()?),
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});
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}
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_ => return Err(self.make_error(TokenKind::Identifier("Argument".into()), next)),
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}
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}
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Ok(args)
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}
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fn parse_type(&mut self) -> Result<Type, String> {
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self.match_token(TokenKind::Colon)?;
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let next = self.peek()?;
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let typ = match next.kind {
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TokenKind::Identifier(_) => Type::try_from(self.next()?.raw),
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_ => Err("Expected type".into()),
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}?;
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if let Ok(_) = self.peek_token(TokenKind::SquareBraceOpen) {
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self.match_token(TokenKind::SquareBraceOpen)?;
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self.match_token(TokenKind::SquareBraceClose)?;
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Ok(Type::Array(Box::new(typ)))
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} else {
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Ok(typ)
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}
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}
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fn parse_statement(&mut self) -> Result<Statement, String> {
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let token = self.peek()?;
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let state = match &token.kind {
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TokenKind::Keyword(Keyword::Let) => self.parse_declare(),
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TokenKind::Keyword(Keyword::Return) => self.parse_return(),
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TokenKind::Keyword(Keyword::If) => self.parse_conditional_statement(),
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TokenKind::Keyword(Keyword::While) => self.parse_while_loop(),
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TokenKind::Keyword(Keyword::Break) => self.parse_break(),
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TokenKind::Keyword(Keyword::Continue) => self.parse_continue(),
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TokenKind::Keyword(Keyword::For) => self.parse_for_loop(),
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TokenKind::Identifier(_) => {
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let ident = self.match_identifier()?;
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if let Ok(_) = self.peek_token(TokenKind::BraceOpen) {
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let state = self.parse_function_call(Some(ident))?;
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Ok(Statement::Exp(state))
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} else if let Ok(_) = self.peek_token(TokenKind::Assign) {
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let state = self.parse_assignent(Some(Expression::Variable(ident)))?;
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Ok(state)
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} else if let Ok(_) = self.peek_token(TokenKind::SquareBraceOpen) {
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let expr = self.parse_array_access(Some(ident))?;
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let next = self.peek()?;
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match next.kind {
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TokenKind::Assign => self.parse_assignent(Some(expr)),
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_ => Ok(Statement::Exp(expr)),
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}
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} else if let Ok(_) = BinOp::try_from(self.peek()?.kind) {
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let expr = Expression::Variable(ident.into());
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let state = Statement::Exp(self.parse_bin_op(Some(expr))?);
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Ok(state)
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} else {
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let state = Statement::Exp(Expression::Variable(ident.into()));
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Ok(state)
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}
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}
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TokenKind::Literal(_) => Ok(Statement::Exp(self.parse_expression()?)),
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_ => return Err(self.make_error(TokenKind::Unknown, token)),
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};
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state
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}
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/// Parses a function call from tokens.
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/// The name of the function needs to be passed here, because we have already passed it with our cursor.
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/// If no function name is provided, the next token will be fetched
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fn parse_function_call(&mut self, func_name: Option<String>) -> Result<Expression, String> {
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let name = match func_name {
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Some(name) => name,
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None => self.next()?.raw,
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};
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self.match_token(TokenKind::BraceOpen)?;
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let mut args = Vec::new();
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loop {
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let next = self.peek()?;
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match &next.kind {
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TokenKind::BraceClose => break,
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TokenKind::Comma => {
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let _ = self.next();
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continue;
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}
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TokenKind::Identifier(_) | TokenKind::Literal(_) => {
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args.push(self.parse_expression()?)
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}
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TokenKind::Keyword(Keyword::Boolean) => args.push(self.parse_expression()?),
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TokenKind::SquareBraceOpen => {
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// TODO: Expression parsing currently uses `next` instead of `peek`.
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// We have to eat that token here until that is resolved
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self.match_token(TokenKind::SquareBraceOpen)?;
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args.push(self.parse_array()?);
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}
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_ => {
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return Err(self.make_error(TokenKind::BraceClose, next));
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}
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};
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}
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self.match_token(TokenKind::BraceClose)?;
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Ok(Expression::FunctionCall(name, args))
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}
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fn parse_return(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::Return)?;
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let peeked = self.peek()?;
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match peeked.kind {
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TokenKind::SemiColon => Ok(Statement::Return(None)),
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_ => Ok(Statement::Return(Some(self.parse_expression()?))),
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}
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}
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fn parse_expression(&mut self) -> Result<Expression, String> {
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let token = self.next()?;
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match token.kind {
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TokenKind::BraceOpen => {
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let expr = self.parse_expression()?;
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self.match_token(TokenKind::BraceClose)?;
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Ok(expr)
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}
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TokenKind::Keyword(Keyword::Boolean) => {
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let state = match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(None)?,
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Err(_) => {
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Expression::Bool(token.raw.parse::<bool>().map_err(|e| e.to_string())?)
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}
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};
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Ok(state)
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}
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TokenKind::Literal(Value::Int) => {
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let state = match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(None)?,
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Err(_) => Expression::Int(token.raw.parse::<u32>().map_err(|e| e.to_string())?),
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};
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Ok(state)
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}
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TokenKind::Literal(Value::Str) => {
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let state = match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(None)?,
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Err(_) => Expression::Str(token.raw),
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};
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Ok(state)
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}
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TokenKind::Identifier(val) => {
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let next = self.peek()?;
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let state = match &next.kind {
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TokenKind::BraceOpen => {
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let func_call = self.parse_function_call(Some(val))?;
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match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(Some(func_call))?,
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Err(_) => func_call,
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}
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}
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TokenKind::SquareBraceOpen => {
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let arr = self.parse_array_access(Some(val))?;
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match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(Some(arr))?,
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Err(_) => arr,
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}
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}
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_ => match BinOp::try_from(self.peek()?.kind) {
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Ok(_) => self.parse_bin_op(Some(Expression::Variable(token.raw)))?,
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Err(_) => Expression::Variable(val),
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},
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};
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Ok(state)
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}
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TokenKind::SquareBraceOpen => self.parse_array(),
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other => Err(format!("Expected Expression, found {:?}", other)),
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}
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}
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fn parse_array(&mut self) -> Result<Expression, String> {
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let mut elements = Vec::new();
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loop {
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let next = self.peek()?;
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match next.kind {
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TokenKind::SquareBraceClose => {}
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TokenKind::Literal(Value::Int) => {
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let value = self.next()?.raw.parse::<u32>().map_err(|e| e.to_string())?;
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elements.push(Expression::Int(value));
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}
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_ => {
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let expr = self.parse_expression()?;
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elements.push(expr);
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}
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};
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if self.peek_token(TokenKind::SquareBraceClose).is_ok() {
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break;
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}
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self.match_token(TokenKind::Comma)?;
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}
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self.match_token(TokenKind::SquareBraceClose)?;
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Ok(Expression::Array(elements))
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}
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fn parse_array_access(&mut self, arr_name: Option<String>) -> Result<Expression, String> {
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let name = match arr_name {
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Some(name) => name,
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None => self.next()?.raw,
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};
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self.match_token(TokenKind::SquareBraceOpen)?;
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let expr = self.parse_expression()?;
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self.match_token(TokenKind::SquareBraceClose)?;
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Ok(Expression::ArrayAccess(name, Box::new(expr)))
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}
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fn parse_while_loop(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::While)?;
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let expr = self.parse_expression()?;
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let body = self.parse_block()?;
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Ok(Statement::While(expr, Box::new(body)))
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}
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fn parse_break(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::Break)?;
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Ok(Statement::Break)
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}
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fn parse_continue(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::Continue)?;
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Ok(Statement::Continue)
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}
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fn parse_for_loop(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::For)?;
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let ident = self.match_identifier()?;
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let ident_ty = match self.peek()?.kind {
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TokenKind::Colon => Some(self.parse_type()?),
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_ => None,
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};
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self.match_keyword(Keyword::In)?;
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let expr = self.parse_expression()?;
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let body = self.parse_block()?;
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Ok(Statement::For(
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Variable {
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name: ident,
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ty: ident_ty,
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},
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expr,
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Box::new(body),
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))
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}
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fn parse_conditional_statement(&mut self) -> Result<Statement, String> {
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self.match_keyword(Keyword::If)?;
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let condition = self.parse_expression()?;
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let body = self.parse_block()?;
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match self.peek()? {
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tok if tok.kind == TokenKind::Keyword(Keyword::Else) => {
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let _ = self.next();
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let peeked = self.peek()?;
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let has_else = match &peeked.kind {
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TokenKind::CurlyBracesOpen => Some(self.parse_block()?),
|
|
|
|
_ => None,
|
|
|
|
};
|
|
|
|
|
|
|
|
let else_branch = match has_else {
|
|
|
|
Some(branch) => branch,
|
|
|
|
None => self.parse_conditional_statement()?,
|
|
|
|
};
|
|
|
|
Ok(Statement::If(
|
|
|
|
condition,
|
|
|
|
Box::new(body),
|
|
|
|
Some(Box::new(else_branch)),
|
|
|
|
))
|
|
|
|
}
|
|
|
|
_ => Ok(Statement::If(condition, Box::new(body), None)),
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// In some occurences a complex expression has been evaluated before a binary operation is encountered.
|
|
|
|
/// The following expression is one such example:
|
|
|
|
/// ```
|
|
|
|
/// foo(1) * 2
|
|
|
|
/// ```
|
|
|
|
/// In this case, the function call has already been evaluated, and needs to be passed to this function.
|
|
|
|
fn parse_bin_op(&mut self, lhs: Option<Expression>) -> Result<Expression, String> {
|
|
|
|
let left = match lhs {
|
|
|
|
Some(lhs) => lhs,
|
|
|
|
None => {
|
|
|
|
let prev = self.prev().ok_or_else(|| "Expected Token")?;
|
|
|
|
match &prev.kind {
|
|
|
|
TokenKind::Identifier(_) | TokenKind::Literal(_) | TokenKind::Keyword(_) => {
|
|
|
|
Ok(Expression::try_from(prev)?)
|
|
|
|
}
|
|
|
|
_ => Err(self.make_error(TokenKind::Unknown, prev)),
|
|
|
|
}?
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
let op = self.match_operator()?;
|
|
|
|
|
|
|
|
Ok(Expression::BinOp(
|
|
|
|
Box::from(Expression::try_from(left).map_err(|e| e.to_string())?),
|
|
|
|
op,
|
|
|
|
Box::from(self.parse_expression()?),
|
|
|
|
))
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_declare(&mut self) -> Result<Statement, String> {
|
|
|
|
self.match_keyword(Keyword::Let)?;
|
|
|
|
let name = self.match_identifier()?;
|
|
|
|
let ty = match self.peek()?.kind {
|
|
|
|
TokenKind::Colon => Some(self.parse_type()?),
|
|
|
|
_ => None,
|
|
|
|
};
|
|
|
|
|
|
|
|
match self.peek()?.kind {
|
|
|
|
TokenKind::Assign => {
|
|
|
|
self.match_token(TokenKind::Assign)?;
|
|
|
|
let expr = self.parse_expression()?;
|
|
|
|
Ok(Statement::Declare(Variable { name, ty }, Some(expr)))
|
|
|
|
}
|
|
|
|
_ => Ok(Statement::Declare(Variable { name, ty }, None)),
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_assignent(&mut self, name: Option<Expression>) -> Result<Statement, String> {
|
|
|
|
let name = match name {
|
|
|
|
Some(name) => name,
|
|
|
|
None => Expression::Variable(self.match_identifier()?),
|
|
|
|
};
|
|
|
|
|
|
|
|
self.match_token(TokenKind::Assign)?;
|
|
|
|
|
|
|
|
let expr = self.parse_expression()?;
|
|
|
|
|
|
|
|
Ok(Statement::Assign(Box::new(name), Box::new(expr)))
|
|
|
|
}
|
|
|
|
}
|