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425 lines
15 KiB
425 lines
15 KiB
/** |
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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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while let Err(_) = self.peek_token(TokenKind::CurlyBracesClose) { |
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let statement = self.parse_statement()?; |
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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)) |
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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 { |
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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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_ => { |
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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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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: None, |
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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()?), |
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_ => None, |
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}; |
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let else_branch = match has_else { |
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Some(branch) => branch, |
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None => self.parse_conditional_statement()?, |
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}; |
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Ok(Statement::If( |
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condition, |
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Box::new(body), |
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Some(Box::new(else_branch)), |
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)) |
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} |
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_ => Ok(Statement::If(condition, Box::new(body), None)), |
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} |
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} |
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/// In some occurences a complex expression has been evaluated before a binary operation is encountered. |
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/// The following expression is one such example: |
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/// ``` |
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/// foo(1) * 2 |
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/// ``` |
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/// In this case, the function call has already been evaluated, and needs to be passed to this function. |
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fn parse_bin_op(&mut self, lhs: Option<Expression>) -> Result<Expression, String> { |
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let left = match lhs { |
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Some(lhs) => lhs, |
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None => { |
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let prev = self.prev().ok_or_else(|| "Expected Token")?; |
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match &prev.kind { |
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TokenKind::Identifier(_) | TokenKind::Literal(_) | TokenKind::Keyword(_) => { |
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Ok(Expression::try_from(prev)?) |
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} |
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_ => Err(self.make_error(TokenKind::Unknown, prev)), |
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}? |
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} |
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}; |
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let op = self.match_operator()?; |
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Ok(Expression::BinOp( |
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Box::from(Expression::try_from(left).map_err(|e| e.to_string())?), |
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op, |
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Box::from(self.parse_expression()?), |
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)) |
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} |
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fn parse_declare(&mut self) -> Result<Statement, String> { |
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self.match_keyword(Keyword::Let)?; |
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let name = self.match_identifier()?; |
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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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match self.peek()?.kind { |
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TokenKind::Assign => { |
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self.match_token(TokenKind::Assign)?; |
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let expr = self.parse_expression()?; |
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Ok(Statement::Declare(Variable { name, ty }, Some(expr))) |
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} |
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_ => Ok(Statement::Declare(Variable { name, ty }, None)), |
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} |
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} |
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fn parse_assignent(&mut self, name: Option<Expression>) -> Result<Statement, String> { |
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let name = match name { |
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Some(name) => name, |
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None => Expression::Variable(self.match_identifier()?), |
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}; |
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self.match_token(TokenKind::Assign)?; |
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let expr = self.parse_expression()?; |
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Ok(Statement::Assign(Box::new(name), Box::new(expr))) |
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} |
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}
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