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Sure! So I'm trying to implement this feature: https://github.com/tree-sitter/tree-sitter/issues/982#issuecomment-797812264 https://github.com/tree-sitter/tree-

• devit 6y ago
  It passes cargo check with this change. diff --git a/cli/src/test.rs b/cli/src/test.rs index ac4807bf..8b9882ab 100644 --- a/cli/src/test.rs +++ b/cli/src/test.rs @@ -410,16 +410,17 @@ fn parse_test_content(name: String, content: String, file_path: Option<PathBuf>) .map(|b| String::from_utf8_lossy(b).to_string()) .map(|s| escape_reserved_regex_chars(&s)); - let suffixHeaderPattern : Option<String> = suffix + let suffixHeaderPattern : Option<String> = suffix.as_ref() .map(|s| String::from(r"^===+") + &s + r"\r?\n([^=]*)\r?\n===+" + &s + r"\r?\n"); - let suffixDividerPattern: Option<String> = suffix + let suffixDividerPattern: Option<String> = suffix.as_ref() .map(|s| String::from(r"^---+") + &s + r"\r?\n"); - let headerRegex = suffixHeaderPattern - .and_then(|s| ByteRegexBuilder::new(&s[..]).multi_line(true).build().ok()) - .as_ref() - .unwrap_or(&HEADER_REGEX); + let headerRegexFromSuffixHeaderPattern = suffixHeaderPattern.as_ref() + .and_then(|s| ByteRegexBuilder::new(&s[..]).multi_line(true).build().ok()); + + let headerRegex = headerRegexFromSuffixHeaderPattern + .as_ref().unwrap_or(&HEADER_REGEX); // Identify all of the test descriptions using the `======` headers. for (header_start, header_end) in headerRegex
  • ahelwer 6y ago
    Thank you for this! the .as_ref() seems to solve a lot of the problems, since I guess just doing a straight .map() takes ownership of the contained string.
• estebank 6y ago
  The error output for your code is error[E0382]: use of moved value: `suffix` --> cli/src/test.rs:416:48 | 406 | let suffix = FIRST_HEADER_REGEX | ------ move occurs because `suffix` has type `std::option::Option<std::string::String>`, which does not implement the `Copy` trait ... 414 | .map(|s| String::from(r"^===+") + &s + r"\r?\n([^=]*)\r?\n===+" + &s + r"\r?\n"); | ------------------------------------------------------------------------------- `suffix` moved due to this method call 415 | 416 | let suffixDividerPattern: Option<String> = suffix | ^^^^^^ value used here after move | note: this function consumes the receiver `self` by taking ownership of it, which moves `suffix` --> /Users/ekuber/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/option.rs:451:38 | 451 | pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Option<U> { | ^^^^ error[E0716]: temporary value dropped while borrowed --> cli/src/test.rs:419:23 | 419 | let headerRegex = suffixHeaderPattern | _______________________^ 420 | | .and_then(|s| ByteRegexBuilder::new(&s[..]).multi_line(true).build().ok()) | |__________________________________________________________________________________^ creates a temporary which is freed while still in use 421 | .as_ref() 422 | .unwrap_or(&HEADER_REGEX); | - temporary value is freed at the end of this statement ... 425 | for (header_start, header_end) in headerRegex | ----------- borrow later used here | = note: consider using a `let` binding to create a longer lived value You need to change line 413 to turn `suffix` into an `Option<&str>` to avoid taking ownership of it: let suffixHeaderPattern: Option<String> = suffix .as_ref() .map(...); and you need to change the `headerRegex` extraction to turn it also into an `Option<&str>` from an `Option<String>` by using `.as_ref()` before the `.and_then` call, which lets you avoid the `&s[..]` reborrow, that only lives until the end of that closure: let headerRegex = suffixHeaderPattern .as_ref() .and_then(|s| ByteRegexBuilder::new(s).multi_line(true).build().ok()) .unwrap_or(HEADER_REGEX.clone()); Edit: I would also consider this to be a diagnostics bug, for at least the first case rustc should have suggested .as_ref(). For the second part, the compiler would ideally have pointed at the `&s[..]` as part of the problem, and the sibling comment has the change you likely want. Edit 2: to further drive the point home that this should be a bug, this is the current output for a similar case while I was trying to minimize this: error[E0308]: mismatched types --> src/main.rs:10:22 | 10 | .map(|s| bar(s)); | --- ^ expected `&Struct`, found struct `Struct` | | | help: consider using `as_ref` instead: `as_ref().map` https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=d1744a6e660e39aaff47bc6aec1dae4f https://play.rust-lang.org/?version=stable&mode=debug&editio...