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|
// locals
mod error;
mod traverse;
// std
use std::{
fmt,
ops::Not,
path::{Path, PathBuf},
};
// extern
use error::SimError;
use itertools::{EitherOrBoth, Itertools};
use traverse::PreOrder;
use tree_sitter::{Node, Parser, Tree};
type Result<T> = std::result::Result<T, SimError>;
const THRESHOLD: f64 = 0.6;
// Check if two tree-sitter objects (trees or nodes etc.) are "similar"
pub trait Similarity {
// This function accepts a predicate to filter out nodes,
// for e.g.: trivia such as comments and whitespace may be filtered
// out with `!node.is_extra()`
fn is_similar<P>(&self, other: &Self, predicate: P) -> bool
where
P: Fn(&Node) -> bool;
}
// Representation of a fully parsed file from the filesystem
pub struct ProgramFile {
pub path: PathBuf,
pub src: String,
pub tree: Tree,
pub simhash: u64,
}
impl Similarity for ProgramFile {
fn is_similar<P>(&self, other: &Self, predicate: P) -> bool
where
P: Fn(&Node) -> bool,
{
// The order of traversal is unimportant
let mine = PreOrder::new(&self.tree).filter(|n| predicate(n));
let theirs = PreOrder::new(&other.tree).filter(|n| predicate(n));
// Simultaneously traverse both the trees, and find dissimilarities.
//
// A dissimilarity is when:
// - one tree's traversal is longer than the other
// - the trees have identical traversal lengths but non-identical
// nodes along the traversal
let structurally_similar = mine
.zip_longest(theirs)
.any(|result| match result {
EitherOrBoth::Both(mine, theirs) => mine.kind_id() != theirs.kind_id(),
EitherOrBoth::Left(_) | EitherOrBoth::Right(_) => true,
})
.not();
let textually_similar = (simhash::hash_similarity(self.simhash, other.simhash)) > THRESHOLD;
structurally_similar && textually_similar
}
}
impl fmt::Debug for ProgramFile {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("ProgramFile")
.field("path", &self.path)
.field("src", &self.src.len())
.finish()
}
}
impl ProgramFile {
pub fn new<P: AsRef<Path>>(path: P, parser: &mut Parser) -> Result<Self> {
let src = std::fs::read_to_string(&path)?;
let path = path.as_ref().to_owned();
let tree = parser.parse(&src, None).ok_or(SimError::LanguageNotSet)?;
let simhash = simhash::simhash(&src);
Ok(Self {
path,
src,
tree,
simhash,
})
}
}
#[cfg(test)]
mod test {
use super::*;
use tree_sitter::Parser;
// Utility to quickly bootstrap ProgramFiles
// and run similarity checks
fn is_similar(mine: &str, their: &str) -> bool {
let lang = tree_sitter_javascript::language();
let mut parser = Parser::new();
parser.set_language(lang).unwrap();
let my_program_file = ProgramFile {
path: PathBuf::from("mine"),
src: mine.to_owned(),
tree: parser.parse(&mine, None).unwrap(),
simhash: simhash::simhash(&mine),
};
let their_program_file = ProgramFile {
path: PathBuf::from("their"),
src: their.to_owned(),
tree: parser.parse(&their, None).unwrap(),
simhash: simhash::simhash(&their),
};
my_program_file.is_similar(&their_program_file, |n| !n.is_extra())
}
#[test]
fn trivial() {
assert!(is_similar(
r#"
var x = 2;
"#,
r#"
var y = 5;
"#
))
}
#[test]
fn automorphism() {
assert!(is_similar(
r#"
function(x) {
x * 2
}
"#,
r#"
function(x) {
x * 2
}
"#
))
}
#[test]
fn sample() {
assert!(is_similar(
r#"
var scrapeWebsite = async function scrapeWebsite(website) {
try {
var url = normalizeUrl(website);
var html = await fetch(url).then(function (res) {
return res.text();
});
var $ = load(html);
var handles = {};
module.exports.CONFIG.socialNetworks.forEach(function (socialNetwork) {
handles[socialNetwork] = parse(socialNetwork)($);
})
return handles;
} catch (error) {
throw new Error("Error scraping website data for " + website + ": " + error.message)
}
}
"#,
r#"
var parseWebsite = async function parseWebsite(website) {
try {
var url = normalizeUrl(website);
var html = await fetch(url).then(function (res) {
return res.text();
});
var $ = load(html);
var handles = {};
module.exports.CONFIG.socialNetworks.forEach(function (socialNetwork) {
handles[socialNetwork] = parse(socialNetwork)($);
})
return handles;
} catch (error) {
throw new Error("Error fetching website data for " + website + ": " + error.message)
}
}
"#
))
}
#[test]
fn ignore_comment_trivia() {
assert!(is_similar(
r#"
// doubles x
function(x) {
x * 2
}
"#,
r#"
function(x) {
x * 2 // doubles x
}
"#
))
}
#[test]
fn ignore_whitespace_trivia() {
assert!(is_similar(
r#"
function(x) {
return x * 2;
}
"#,
r#"
function(x ) {
return x * 2;
}
"#
))
}
#[test]
fn dissimilar() {
assert!(!is_similar(
r#"
var t = function(x, y) { }
"#,
r#"
var l = function(x) { }
"#
))
}
}
|
