kconfig-parser 0.1.1

/*
 Cargo KConfig - KConfig parser
 Copyright (C) 2022  Sjoerd van Leent

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Licensed under the Apache License, Version 2.0 (the "License"); you may not use
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The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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*/

//! This file contains the pub structures necessary for the lexer
//! to lex the tokens found within a Kconfig file.

use std::fmt::Display;

/// An equality operator is used for testing two expressions. These
/// expressions should be valid expressions according to the Kconfig
/// grammar.
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum EqualityOperator {
    /// Lesser than or equal to (<=)
    Lte,
    /// Greater than or equal to (>=)
    Lt,
    /// Lesser than (<)
    Gte,
    /// Greater than (>)
    Gt,
    /// Equal to (==)
    Eq,
    /// Not equal to (!=)
    Ne,
}

impl Display for EqualityOperator {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            EqualityOperator::Lte => f.write_str("<="),
            EqualityOperator::Lt => f.write_str("<"),
            EqualityOperator::Gte => f.write_str(">="),
            EqualityOperator::Gt => f.write_str(">"),
            EqualityOperator::Eq => f.write_str("=="),
            EqualityOperator::Ne => f.write_str("!="),
        }
    }
}

#[derive(Debug, PartialEq, Eq, Clone)]
pub enum Keyword {
    /// source
    Source,

    /// mainmenu
    Mainmenu,
    /// config
    Config,
    /// menuconfig
    Menuconfig,
    /// choice
    Choice,
    /// endchoide
    Endchoice,
    /// menu
    Menu,
    /// endmenu
    Endmenu,

    /// if
    If,
    /// endif
    Endif,

    /// bool
    Bool,
    /// def_bool
    DefBool,
    /// tristate
    Tristate,
    /// def_tristate
    DefTristate,
    /// string
    String,
    /// hex
    Hex,
    /// int
    Int,

    /// default
    Default,

    /// depends
    Depends,
    /// on
    On,
    /// select
    Select,
    /// imply
    Imply,

    /// visible
    Visible,

    /// range
    Range,

    /// prompt
    Prompt,
    /// comment
    Comment,
}

impl Display for Keyword {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Keyword::Source => f.write_str("source"),
            Keyword::Mainmenu => f.write_str("mainmenu"),
            Keyword::Config => f.write_str("config"),
            Keyword::Menuconfig => f.write_str("menuconfic"),
            Keyword::Choice => f.write_str("choice"),
            Keyword::Endchoice => f.write_str("endchoice"),
            Keyword::Menu => f.write_str("menu"),
            Keyword::Endmenu => f.write_str("endmenu"),
            Keyword::If => f.write_str("if"),
            Keyword::Endif => f.write_str("endif"),
            Keyword::Bool => f.write_str("bool"),
            Keyword::DefBool => f.write_str("def_bool"),
            Keyword::Tristate => f.write_str("tristate"),
            Keyword::DefTristate => f.write_str("def_tristate"),
            Keyword::String => f.write_str("string"),
            Keyword::Hex => f.write_str("hex"),
            Keyword::Int => f.write_str("int"),
            Keyword::Default => f.write_str("default"),
            Keyword::Depends => f.write_str("depends"),
            Keyword::On => f.write_str("on"),
            Keyword::Select => f.write_str("select"),
            Keyword::Imply => f.write_str("imply"),
            Keyword::Visible => f.write_str("visible"),
            Keyword::Range => f.write_str("range"),
            Keyword::Prompt => f.write_str("prompt"),
            Keyword::Comment => f.write_str("comment"),
        }
    }
}

/// There are a certain amount of basic tokens found within a stream
/// of tokens belonging to a Kconfig configuration specification.
/// These tokens are outlined here.
#[derive(Debug, Eq, PartialEq, Clone)]
pub enum Lexicon {
    /// Keywords such as config, menuconfig, if, comment, source ...
    Keyword(Keyword),
    /// Identifier, specifically used for assignment and evaluation
    Identifier(String),
    /// Strings, encapsulated in double quotes
    String(String),
    /// Help text, indented when a "Help" section was started
    Help(String),
    /// An equality operator, such as <=, ==, etc.
    EqualityOperator(EqualityOperator),
    /// An immediate assignment, e.g.: :=
    ImmediateAssignment,
    /// A normal assignment, e.g.: =
    Assignment,
    /// An appendage assignment, e.g.: +=
    AppendAssignment,
    /// An inverse of an expression
    Not,
    /// Start a macro definition with "$("
    MacroOpen,
    /// Start a normal definition with "("
    Open,
    /// Ends a definition (either macro or normal) with ")"
    Close,
    /// A comma, typically used as an argument separator
    Comma,
    /// End of transmission, used when no more tokens can be found
    EOT,
    /// Error, used when the found token is illegal
    Error(String),
    /// The '&&' expression
    And,
    /// The '||' expression
    Or,
}

impl Display for Lexicon {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Lexicon::Keyword(k) => f.write_str(&format!("{}", k)),
            Lexicon::Identifier(s) => f.write_str(s),
            Lexicon::String(s) => f.write_str(s),
            Lexicon::Help(s) => f.write_str(s),
            Lexicon::EqualityOperator(o) => f.write_str(&format!("{}", o)),
            Lexicon::ImmediateAssignment => f.write_str(":="),
            Lexicon::Assignment => f.write_str("="),
            Lexicon::AppendAssignment => f.write_str("+="),
            Lexicon::Not => f.write_str("+="),
            Lexicon::MacroOpen => f.write_str("$("),
            Lexicon::Open => f.write_str("("),
            Lexicon::Close => f.write_str(")"),
            Lexicon::Comma => f.write_str(","),
            Lexicon::EOT => f.write_str("[End Of Transmission/File]"),
            Lexicon::Error(s) => f.write_str(&format!("Error: {}", s)),
            Lexicon::And => f.write_str("&"),
            Lexicon::Or => f.write_str("|"),
        }
    }
}

/// A token describes the found verb, the column and line where it has
/// been found.
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Token {
    /// Contains the specific token from the lexicon
    term: Lexicon,
    /// Contains the column position of the token from the current
    /// position, if line > 0, then the column position will be from
    /// the start of the line the token was found on.
    column: usize,
    /// Contains the line number of the token from the current
    /// position.
    line: usize,
    /// Contains the raw string of the token
    raw: String,
}

impl Display for Token {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(&format!("{}", self.term))
    }
}

impl Token {
    /// Creates a token, using a term from the `Lexicon`, at the given column
    /// (minus the term), at the specified line with the given string. The string
    /// is only used to determine the length of the token.
    pub(super) fn create(term: Lexicon, column: usize, line: usize, raw: &str) -> Self {
        Self {
            term,
            column,
            line,
            raw: raw.to_string(),
        }
    }

    /// Creates a token representing an error, at the given column (minus the term),
    /// at the specified line with the given string. The string is only used to
    /// determine the length of the token.
    pub(crate) fn create_error(column: usize, line: usize, s: &str) -> Self {
        Self {
            term: Lexicon::Error(s.to_string()),
            column,
            line,
            raw: s.to_string(),
        }
    }

    /// Creates a token representing end-of-transmission, typically at the end of
    /// the file, end of stream or end of buffer, at the given column and line.
    pub(super) fn create_eot(column: usize, line: usize) -> Self {
        Self {
            term: Lexicon::EOT,
            column,
            line,
            raw: "".to_owned(),
        }
    }

    pub fn term(&self) -> Lexicon {
        self.term.clone()
    }

    pub fn column(&self) -> usize {
        self.column
    }

    pub fn line(&self) -> usize {
        self.line
    }

    pub fn raw(&self) -> String {
        self.raw.clone()
    }

    /// Returns if the token's term indicates EOT (End of transmission,
    /// most likely End of file).
    pub fn eot(&self) -> bool {
        match self.term {
            Lexicon::EOT => return true,
            _ => return false,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_token_creation() {
        let expected = Token {
            term: Lexicon::EOT,
            column: 0,
            line: 0,
            raw: "".to_owned(),
        };
        let got = Token::create(Lexicon::EOT, 0, 0, &"");
        assert_eq!(expected, got);
    }
}