1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

use std::io::{self, Write};
use std::path::PathBuf;

use crate::checker::Checker;
use crate::node::Node;

use crate::tools::*;
use crate::traits::*;

const CR: [u8; 8192] = [b'\n'; 8192];

/// Removes comments from a code.
pub fn rm_comments<T: ParserTrait>(parser: &T) -> Option<Vec<u8>> {
    let node = parser.get_root();
    let mut stack = Vec::new();
    let mut cursor = node.object().walk();
    let mut spans = Vec::new();

    stack.push(node);

    while let Some(node) = stack.pop() {
        if T::Checker::is_comment(&node) && !T::Checker::is_useful_comment(&node, parser.get_code())
        {
            let lines = node.object().end_position().row - node.object().start_position().row;
            spans.push((node.object().start_byte(), node.object().end_byte(), lines));
        } else {
            cursor.reset(node.object());
            if cursor.goto_first_child() {
                loop {
                    stack.push(Node::new(cursor.node()));
                    if !cursor.goto_next_sibling() {
                        break;
                    }
                }
            }
        }
    }
    if !spans.is_empty() {
        Some(remove_from_code(parser.get_code(), spans))
    } else {
        None
    }
}

fn remove_from_code(code: &[u8], mut spans: Vec<(usize, usize, usize)>) -> Vec<u8> {
    let mut new_code = Vec::with_capacity(code.len());
    let mut code_start = 0;
    for (start, end, lines) in spans.drain(..).rev() {
        new_code.extend(&code[code_start..start]);
        if lines != 0 {
            if lines <= CR.len() {
                new_code.extend(&CR[..lines]);
            } else {
                new_code.resize_with(new_code.len() + lines, || b'\n');
            }
        }
        code_start = end;
    }
    if code_start < code.len() {
        new_code.extend(&code[code_start..]);
    }
    new_code
}

/// Configuration options for removing comments from a code.
pub struct CommentRmCfg {
    /// If `true`, the modified code is saved on a file
    pub in_place: bool,
    /// Path to output file
    pub path: PathBuf,
}

pub struct CommentRm {
    _guard: (),
}

impl Callback for CommentRm {
    type Res = std::io::Result<()>;
    type Cfg = CommentRmCfg;

    fn call<T: ParserTrait>(cfg: Self::Cfg, parser: &T) -> Self::Res {
        if let Some(new_source) = rm_comments(parser) {
            if cfg.in_place {
                write_file(&cfg.path, &new_source)?;
            } else if let Ok(new_source) = std::str::from_utf8(&new_source) {
                println!("{}", new_source);
            } else {
                io::stdout().write_all(&new_source)?;
            }
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::path::PathBuf;

    use crate::{CcommentParser, ParserTrait};

    use super::rm_comments;

    const SOURCE_CODE: &str = "/* Remove this code block */\n\
                               int a = 42; // Remove this comment\n\
                               // Remove this comment\n\
                               int b = 42;\n\
                               /* Remove\n\
                                * this\n\
                                * comment\n\
                                */";

    const SOURCE_CODE_NO_COMMENTS: &str = "\n\
                                           int a = 42; \n\
                                           \n\
                                           int b = 42;\n\
                                           \n\
                                           \n\
                                           \n\
                                           \n";

    #[test]
    fn ccomment_remove_comments() {
        let path = PathBuf::from("foo.c");
        let mut trimmed_bytes = SOURCE_CODE.as_bytes().to_vec();
        trimmed_bytes.push(b'\n');
        let parser = CcommentParser::new(trimmed_bytes, &path, None);

        let no_comments = rm_comments(&parser).unwrap();

        assert_eq!(no_comments.as_slice(), SOURCE_CODE_NO_COMMENTS.as_bytes());
    }
}