69 lines
1.8 KiB
Rust
69 lines
1.8 KiB
Rust
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use rustc::lint::*;
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use rustc_front::hir::*;
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use utils::{get_parent_expr, is_exp_equal, span_lint};
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/// **What it does:** This lint checks for consecutive `ifs` with the same condition. This lint is
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/// `Warn` by default.
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///
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/// **Why is this bad?** This is probably a copy & paste error.
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///
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/// **Known problems:** Hopefully none.
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///
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/// **Example:** `if a == b { .. } else if a == b { .. }`
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declare_lint! {
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pub IFS_SAME_COND,
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Warn,
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"consecutive `ifs` with the same condition"
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}
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#[derive(Copy, Clone, Debug)]
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pub struct CopyAndPaste;
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impl LintPass for CopyAndPaste {
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fn get_lints(&self) -> LintArray {
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lint_array![
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IFS_SAME_COND
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]
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}
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}
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impl LateLintPass for CopyAndPaste {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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// skip ifs directly in else, it will be checked in the parent if
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if let Some(&Expr{node: ExprIf(_, _, Some(ref else_expr)), ..}) = get_parent_expr(cx, expr) {
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if else_expr.id == expr.id {
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return;
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}
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}
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let conds = condition_sequence(expr);
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for (n, i) in conds.iter().enumerate() {
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for j in conds.iter().skip(n+1) {
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if is_exp_equal(cx, i, j) {
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span_lint(cx, IFS_SAME_COND, j.span, "this if as the same condition as a previous if");
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}
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}
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}
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}
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}
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/// Return the list of conditions expression in a sequence of `if/else`.
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/// Eg. would return `[a, b]` for the expression `if a {..} else if b {..}`.
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fn condition_sequence(mut expr: &Expr) -> Vec<&Expr> {
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let mut result = vec![];
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while let ExprIf(ref cond, _, ref else_expr) = expr.node {
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result.push(&**cond);
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if let Some(ref else_expr) = *else_expr {
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expr = else_expr;
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}
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else {
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break;
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}
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}
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result
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}
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