big-code-analysis 2.0.0

// Per-language metric and AST modules deliberately consume the macro-
// generated tree-sitter token enums via `use crate::*` and `use Foo::*`
// inside match expressions — explicit imports would list dozens of
// variants per arm and obscure the per-language token sets that are the
// point of these files. Allowed at the module level rather than per
// function so the per-language impl blocks stay readable.
#![allow(clippy::wildcard_imports, clippy::enum_glob_use)]

use std::marker::PhantomData;
use std::path::Path;
use std::sync::Arc;

use crate::abc::Abc;
use crate::checker::Checker;
use crate::cognitive::Cognitive;
use crate::cyclomatic::Cyclomatic;
use crate::halstead::Halstead;
use crate::loc::Loc;
use crate::mi::Mi;
use crate::nargs::NArgs;
use crate::nexits::Exit;
use crate::nom::Nom;
use crate::npa::Npa;
use crate::npm::Npm;
use crate::tokens::Tokens;
use crate::wmc::Wmc;

use crate::alterator::Alterator;
use crate::getter::Getter;

use crate::c_macro;
use crate::langs::*;
use crate::node::{Node, Tree};
use crate::preproc::{PreprocResults, get_macros};
use crate::traits::*;

/// Parsed source plus the tree-sitter `Tree` for a given language `T`.
///
/// Construct with [`Parser::new`] and feed the result into the metric,
/// alterator, or AST-dump entry points. The type parameter `T` is one
/// of the language code tags (`RustCode`, `PythonCode`, etc.) declared
/// by the internal `mk_code!` macro.
#[derive(Debug)]
pub(crate) struct Parser<
    T: LanguageInfo
        + Alterator
        + Checker
        + Getter
        + Abc
        + Cognitive
        + Cyclomatic
        + Exit
        + Halstead
        + Loc
        + Mi
        + NArgs
        + Nom
        + Npa
        + Npm
        + Tokens
        + Wmc,
> {
    code: Vec<u8>,
    tree: Tree,
    phantom: PhantomData<T>,
}

type FilterFn = dyn Fn(&Node) -> bool;

/// Collection of node-matching predicates used by the AST-walking
/// metric and dump routines to decide whether to visit a node.
pub(crate) struct Filter {
    filters: Vec<Box<FilterFn>>,
}

impl Filter {
    /// Returns `true` if *any* of the configured predicates matches `node`.
    #[must_use]
    pub fn any(&self, node: &Node) -> bool {
        for f in &self.filters {
            if f(node) {
                return true;
            }
        }
        false
    }
}

#[inline]
fn get_fake_code<T: LanguageInfo>(
    code: &[u8],
    path: &Path,
    pr: Option<Arc<PreprocResults>>,
) -> Option<Vec<u8>> {
    if let Some(pr) = pr {
        match T::lang() {
            // The C-family languages share the preprocessor
            // macro-replacement pass: `C` (#721), upstream `Cpp`, and the
            // `Mozcpp` Gecko dialect (#720) all need `#define` expansion.
            LANG::C | LANG::Cpp | LANG::Mozcpp => {
                let macros = get_macros(path, &pr.files);
                c_macro::replace(code, &macros)
            }
            _ => None,
        }
    } else {
        None
    }
}

impl<
    T: 'static
        + LanguageInfo
        + Alterator
        + Checker
        + Getter
        + Abc
        + Cognitive
        + Cyclomatic
        + Exit
        + Halstead
        + Loc
        + Mi
        + NArgs
        + Nom
        + Npa
        + Npm
        + Tokens
        + Wmc,
> ParserTrait for Parser<T>
{
    type Checker = T;
    type Getter = T;
    type Cognitive = T;
    type Cyclomatic = T;
    type Halstead = T;
    type Loc = T;
    type Nom = T;
    type Mi = T;
    type NArgs = T;
    type Exit = T;
    type Wmc = T;
    type Abc = T;
    type Npm = T;
    type Npa = T;
    type Tokens = T;

    fn new(code: Vec<u8>, path: &Path, pr: Option<Arc<PreprocResults>>) -> Self {
        let fake_code = get_fake_code::<T>(&code, path, pr);
        let code = if let Some(fake) = fake_code {
            fake
        } else {
            code
        };

        let tree = Tree::new::<T>(&code);

        Self {
            code,
            tree,
            phantom: PhantomData,
        }
    }

    #[inline]
    fn root(&self) -> Node<'_> {
        self.tree.get_root()
    }

    #[inline]
    fn code(&self) -> &[u8] {
        &self.code
    }

    fn filters(&self, requested: &[String]) -> Filter {
        let mut res: Vec<Box<FilterFn>> = Vec::new();
        for f in requested {
            let f = f.as_str();
            match f {
                "all" => res.push(Box::new(|_: &Node| -> bool { true })),
                "call" => res.push(Box::new(T::is_call)),
                "comment" => res.push(Box::new(T::is_comment)),
                "error" => res.push(Box::new(T::is_error)),
                "string" => res.push(Box::new(T::is_string)),
                "function" => res.push(Box::new(T::is_func)),
                _ => {
                    if let Ok(n) = f.parse::<u16>() {
                        // A numeric `-t`/`--type` value matches by raw
                        // tree-sitter `kind_id` rather than node-type name.
                        // This is an escape hatch for grammar inspection
                        // (matching a kind that has no stable name, or one
                        // the string path mis-resolves), but `kind_id` is an
                        // index into the grammar's symbol table and is *not*
                        // stable across grammar versions — the same number
                        // names different nodes after a bump, and `-t 0` is
                        // the end/ERROR sentinel. Documented as unstable in
                        // big-code-analysis-book/src/commands/nodes.md; the
                        // string (`kind()`) path below is the supported one.
                        res.push(Box::new(move |node: &Node| -> bool { node.kind_id() == n }));
                    } else {
                        // Exact match on `node.kind()` — the CLI documents
                        // `find <NODE>` / `count <NODE_TYPE>` as searching
                        // for a specific node type, not a substring (see
                        // big-code-analysis-book/src/commands/nodes.md and
                        // issue #293).
                        let f = f.to_owned();
                        res.push(Box::new(move |node: &Node| -> bool { node.kind() == f }));
                    }
                }
            }
        }
        if res.is_empty() {
            res.push(Box::new(|_: &Node| -> bool { true }));
        }

        Filter { filters: res }
    }
}

impl<
    T: 'static
        + LanguageInfo
        + Alterator
        + Checker
        + Getter
        + Abc
        + Cognitive
        + Cyclomatic
        + Exit
        + Halstead
        + Loc
        + Mi
        + NArgs
        + Nom
        + Npa
        + Npm
        + Tokens
        + Wmc,
> Parser<T>
{
    /// Builds a [`Parser`] from a pre-parsed [`tree_sitter::Tree`]
    /// and the matching source bytes.
    ///
    /// Use this when the caller already drives `tree-sitter` for
    /// other purposes (e.g. an editor doing incremental reparsing)
    /// and wants the metric walker to reuse the parse instead of
    /// running its own. The standard byte-based entry point
    /// remains [`ParserTrait::new`].
    ///
    /// The supplied `tree` must have been produced from `code` with
    /// the tree-sitter language matching `T` — typically obtained
    /// via [`crate::LANG::tree_sitter_language`]. A mismatch is
    /// not `unsafe`, but metric values will be nonsensical because
    /// the tree's `kind_id` values will not correspond to the per-
    /// language enum the metric `compute` functions match on.
    #[must_use]
    pub fn from_tree(tree: tree_sitter::Tree, code: Vec<u8>) -> Self {
        Self {
            code,
            tree: Tree::from_ts_tree(tree),
            phantom: PhantomData,
        }
    }

    /// Borrow the underlying [`tree_sitter::Tree`] for callers that
    /// want to drive their own traversal alongside the metric walker.
    ///
    /// Doc-hidden because `Parser` itself is hidden from the rendered
    /// surface; the stable spelling of this accessor is
    /// [`crate::Ast::as_tree_sitter`].
    #[must_use]
    pub fn ts_tree(&self) -> &tree_sitter::Tree {
        self.tree.as_ts_tree()
    }
}

#[cfg(test)]
mod tests {
    use crate::count::count;
    use crate::langs::PythonParser;
    use crate::traits::ParserTrait;
    use std::path::PathBuf;

    fn parse_python(source: &str) -> PythonParser {
        PythonParser::new(source.as_bytes().to_vec(), &PathBuf::from("t.py"), None)
    }

    fn count_kind(source: &str, filter: &str) -> usize {
        count(&parse_python(source), &[filter.to_string()]).0
    }

    // Regression for #293: a named filter that is not a hardcoded
    // keyword (`all`/`call`/`comment`/`error`/`string`/`function`) and
    // not a numeric `kind_id` must match `node.kind()` exactly, not via
    // substring containment.

    #[test]
    fn get_filters_exact_match_hits_named_kind() {
        // Python's `if`/`elif`/`else` clauses each appear as their own
        // `if_statement` / `elif_clause` / `else_clause` nodes. Filter
        // `if_statement` should match exactly one node here.
        let src = "if x:\n    pass\nelif y:\n    pass\nelse:\n    pass\n";
        assert_eq!(count_kind(src, "if_statement"), 1);
    }

    #[test]
    fn get_filters_no_substring_match() {
        // Filter `expression` must not match `expression_statement`,
        // `binary_expression`, etc. Under the old substring behaviour
        // every expression-bearing node would count; under exact-match
        // there is no node literally named `expression` in this source.
        let src = "x = 1 + 2\ny = foo(3)\n";
        assert_eq!(
            count_kind(src, "expression"),
            0,
            "exact match must not collapse all *_expression kinds"
        );
        // Sanity: `assignment` is a real node kind in tree-sitter-python
        // and matches exactly twice (one per statement).
        assert_eq!(count_kind(src, "assignment"), 2);
    }

    #[test]
    fn get_filters_unknown_kind_returns_empty() {
        // A filter that names no real node kind matches nothing — the
        // previous substring behaviour would still return 0 here, but
        // pinning it guards against a future regression that re-enables
        // fuzzy matching.
        let src = "x = 1\n";
        assert_eq!(count_kind(src, "definitely_not_a_python_kind"), 0);
    }
}