diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/parser.rs | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/src/parser.rs b/src/parser.rs index d6eb69d..95807c1 100644 --- a/src/parser.rs +++ b/src/parser.rs @@ -1,29 +1,5 @@ use crate::ast::*; -// (λx:T.y): T z -pub fn parse(input: &str) -> Expression { - match parse_lambda(input) { - Ok(expr) => return expr, - Err(e) => println!("invalid expression! {:?}", e) - } - return Expression::Constant { term: Term::Unit() }; -} - -/// Parses a Nim-like language into an AST. -pub fn parse_file(path: &str) -> Vec<Expression> { - match std::fs::read_to_string(path) { - Ok(file) => match lex(&file) { - Ok(input) => match parse_lang(&input) { - Ok(expr) => return expr, - Err(e) => println!("failed to parse file! {:?}", e), - }, - Err(e) => println!("failed to lex file! {:?}", e), - }, - Err(e) => println!("failed to read file! {:?}", e), - } - return Vec::new(); -} - /// Parses a lambda-calculus-like language into an AST. pub fn parse_lambda(input: &str) -> Result<Expression, peg::error::ParseError<peg::str::LineCol>> { // this is kinda awful, i miss my simple nim pegs @@ -119,200 +95,8 @@ pub fn parse_lambda(input: &str) -> Result<Expression, peg::error::ParseError<pe = e:(unbracketed() / bracketed()) { e } - // pub rule ast() -> Vec<Expression> - // = expr() ** ("\n"+) } } return lambda::expr(input.trim()); } -/// Converts a whitespace-indented language into a regular bracketed language for matching with PEGs -/// Then, tokens are known to be separated by [\n ]+ (except strings. problem for later.) -pub fn lex(input: &str) -> Result<String, &'static str> { - #[derive(Eq, PartialEq)] - enum Previous { - Start, - Block, - Line, - } - struct State { - blank: bool, // is the line entirely whitespace so far? - level: usize, // current indentation level - count: usize, // current whitespace count - previous: Previous, - comment: bool // is the current line a comment? - } - let indent_size: usize = 2; - - let mut state = State { blank: true, level: 0, count: 0, previous: Previous::Start, comment: false }; - let mut buffer = String::new(); - let mut result = String::new(); - - // wow lexers are hard - for c in input.chars() { - match c { - '\n' => { - if !buffer.is_empty() { - if state.count == state.level { - if state.previous != Previous::Start { - result.push(';'); - result.push('\n'); - } - state.previous = Previous::Line; - } else if state.level + indent_size == state.count { - result.push(' '); - result.push('{'); - result.push('\n'); - state.level = state.count; - state.previous = Previous::Line; - } else if state.count > state.level + indent_size { - return Err("invalid jump in indentation"); - } else if state.count % indent_size != 0 { - return Err("incorrect indentation offset, must be a multiple of indent_size"); - } else if state.level > state.count { - while state.level > state.count { - if state.previous == Previous::Line { - result.push(';'); - } - state.level -= indent_size; - result.push('\n'); - result.push_str(&" ".repeat(state.level)); - result.push('}'); - result.push(';'); - state.previous = Previous::Block; - } - result.push('\n'); - } else { - return Err("unknown indentation error"); - } - - result.push_str(&" ".repeat(state.count)); - result.push_str(&buffer); - - state.count = 0; - state.comment = false; - buffer.clear(); - } - state.blank = true; - }, - ' ' if state.blank => { - state.count += 1; - }, - '#' => { - state.blank = false; - state.comment = true; - }, - _ => { - if state.blank { - state.blank = false; - } - if !state.comment { - buffer.push(c); - } - }, - } - } - if state.previous == Previous::Line { - result.push(';'); - } - while state.level != 0 { - state.level -= 2; - result.push('\n'); - result.push_str(&" ".repeat(state.level)); - result.push('}'); - result.push(';'); - } - return Ok(result); -} - -/// Parses a simple language with bracket-based indentation and end-of-term semicolons. -/// The lex() function can turn an indentation-based language into a language recognizable by this. -#[allow(unused_variables)] -pub fn parse_lang(input: &str) -> Result<Vec<Expression>, peg::error::ParseError<peg::str::LineCol>> { - peg::parser! { - grammar puck() for str { - // whitespace - rule w() = ("\n" / " ")+ - // identifiers - rule ident() -> String = i:['a'..='z' | 'A'..='Z' | '0'..='9']+ { - i.iter().collect::<String>() - } - // constants - rule cons() -> Expression = p:"-"? c:['0'..='9']+ { - let value = c.iter().collect::<String>().parse::<usize>().unwrap(); - Expression::Constant { - term: if let Some(_) = p { - Term::Integer(-1 * isize::try_from(value).unwrap()) - } else { - Term::Natural(value) - } - } - } - // types - rule primitive() -> Type = k:$("empty" / "unit" / "bool" / "nat" / "int") { - match k { - "empty" => Type::Empty, - "unit" => Type::Unit, - "bool" => Type::Boolean, - "nat" => Type::Natural, - "int" => Type::Integer, - _ => Type::Empty // never happens - } - } - // fixme: parenthesis necessary, left-recursion issue - rule function() -> Type = "(" w()? f:kind() w()? "->" w()? t:kind() w()? ")" { - Type::Function { from: Box::new(f), to: Box::new(t) } - } - // todo: records, etc - rule kind() -> Type - = k:(function() / primitive()) { - k - } - // fixme: cannot say e:(expr()), left-recursion issue - rule ann() -> Expression - = e:(cond() / abs() / app() / cons() / var()) w()? ":" w() k:kind() { - Expression::Annotation { - expr: Box::new(e), - kind: k - } - } - rule var() -> Expression - = v:ident() { - Expression::Variable { - id: v - } - } - // todo: multiple parameters pls - rule abs() -> Expression - = "func" w() n:ident() w()? "(" p:ident() ")" w()? ":" w()? k:function() w() "=" w() "{" w() f:expr() w() "}" { - Expression::Annotation { - expr: Box::new(Expression::Abstraction { param: p, func: Box::new(f) }), - kind: k - } - } - // fixme: this requires, uh, refactoring the ast... - rule app() -> Expression - = f:ident() "(" a:expr() ")" { - Expression::Application { - func: Box::new(Expression::Variable { id: f }), - arg: Box::new(a) - } - } - rule cond() -> Expression - = "if" w() c:expr() w() "=" w() "{" w() t:expr() w() "};" w() "else" w() "=" w() "{" w() e:expr() w() "}" { - Expression::Conditional { - if_cond: Box::new(c), - if_then: Box::new(t), - if_else: Box::new(e) - } - } - pub rule expr() -> Expression - = e:(ann() / cond() / abs() / app() / cons() / var()) ";" { - e - } - pub rule file() -> Vec<Expression> - = expr() ++ "\n" - } - } - return puck::file(input); -} |