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#[macro_use]
extern crate pest_derive;
extern crate from_pest;
#[macro_use]
extern crate pest_ast;
extern crate pest;
mod parser {
#[derive(Parser)]
#[grammar = "grammar.pest"]
pub struct Parser;
}
mod ast {
use super::parser::Rule;
use pest::Span;
fn span_into_str(span: Span) -> &str {
span.as_str()
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::program))]
pub struct Program {
pub statements: Vec<Statement>,
eoi: EOI,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::statement))]
pub enum Statement {
Definition(Definition),
Expression(Expression),
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::definition))]
pub struct Definition {
pub symbols: Vec<Symbol>,
pub expression: Expression,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::expression))]
pub struct Expression {
pub nodes: Vec<ExpressionNode>,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::expression_node))]
pub enum ExpressionNode {
Symbol(Symbol),
Builtin(Builtin),
IntegerLiteral(IntegerLiteral),
Expression(Expression),
}
#[derive(Debug, FromPest, Copy, Clone)]
#[pest_ast(rule(Rule::builtin))]
pub enum Builtin {
SumOp,
SubtractOp,
DivideOp,
MultiplyOp,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::integer_literal))]
pub struct IntegerLiteral {
#[pest_ast(outer(with(span_into_str), with(str::parse::<i64>), with(Result::unwrap)))]
pub value: i64,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::symbol))]
pub struct Symbol {
#[pest_ast(outer(with(span_into_str), with(String::from)))]
pub value: String,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::EOI))]
struct EOI;
}
mod runtime {
use super::ast;
use std::collections::HashMap;
pub enum RuntimeExpression {
Integer(i64),
BuiltinFunction(ast::Builtin, Box<RuntimeExpression>),
}
pub fn evaluate(ast: &ast::Program) {
let mut _symbol_table: HashMap<String, RuntimeExpression> = HashMap::new();
fn evaluate_nonary(node: &ast::ExpressionNode) -> Box<RuntimeExpression> {
match node {
ast::ExpressionNode::IntegerLiteral(literal) => {
Box::new(RuntimeExpression::Integer(literal.value))
}
_ => todo!("_ case of evaluate_nonary"),
}
}
fn evaluate_unary(
node: &ast::ExpressionNode,
arg: &ast::ExpressionNode,
) -> Box<RuntimeExpression> {
let evaluated_arg = evaluate_expression_node(arg);
match node {
ast::ExpressionNode::Builtin(builtin) => {
Box::new(RuntimeExpression::BuiltinFunction(*builtin, evaluated_arg))
}
_ => todo!("_ case of evaluate_unary"),
}
}
fn evaluate_expression_node(node: &ast::ExpressionNode) -> Box<RuntimeExpression> {
match node {
ast::ExpressionNode::Expression(expr) => evaluate_expression(expr),
_ => todo!("_ case of evaluate_expression_node"),
}
}
fn evaluate_expression(expression: &ast::Expression) -> Box<RuntimeExpression> {
let nodes = &expression.nodes;
return match nodes.len() {
1 => evaluate_nonary(&nodes[0]),
2 => evaluate_unary(&nodes[0], &nodes[1]),
_ => todo!("_ case of evaluate_expression"),
};
}
for statement in &ast.statements {
let runtime_expr = match statement {
ast::Statement::Expression(expression) => evaluate_expression(&expression),
ast::Statement::Definition(_) => {
panic!("unsupported statement type: definition")
}
};
match *runtime_expr {
RuntimeExpression::Integer(value) => println!("{}", value),
RuntimeExpression::BuiltinFunction(builtin, _arg) => match builtin {
_ => todo!("_ case of runtime_expr eval handling"),
},
}
}
}
}
fn main() {
use ast::Program;
use from_pest::FromPest;
use pest::Parser;
use std::fs;
let unparsed_file = fs::read_to_string("samples/sample1.code").expect("cannot read file");
let mut parse_tree =
parser::Parser::parse(parser::Rule::program, &unparsed_file).expect("unsuccessful parse");
println!("parse tree = {:#?}", parse_tree);
let syntax_tree: Program = Program::from_pest(&mut parse_tree).expect("infallible");
println!("syntax tree = {:#?}", syntax_tree);
runtime::evaluate(&syntax_tree);
// let tokens = program.
// for token in program.tokens() {
// println!("{:?}", token);
// }
// println!("{}", program)
// for statement in program.into_inner() {
// match statement.as_rule() {
// Rule::statement => {
// println!("{}", statement.as_str());
// }
// Rule::EOI => (),
// _ => unreachable!(),
// }
// }
// println!("Sum of fields: {}", field_sum);
// println!("Number of records: {}", record_count);
}
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