22 lines
888 B
Rust
22 lines
888 B
Rust
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use crate::parser::Source;
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/// Check if the child string slice is a slice of the parent string slice.
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fn is_slice_of(parent: &str, child: &str) -> bool {
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let parent_start = parent.as_ptr() as usize;
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let parent_end = parent_start + parent.len();
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let child_start = child.as_ptr() as usize;
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let child_end = child_start + child.len();
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child_start >= parent_start && child_end <= parent_end
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}
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/// Get the offset into source that the rust object exists at.
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///
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/// These offsets are zero-based unlike the elisp ones.
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pub fn get_offsets<'s, S: Source<'s>>(source: &'s str, rust_object: &'s S) -> (usize, usize) {
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let rust_object_source = rust_object.get_source();
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assert!(is_slice_of(source, rust_object_source));
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let offset = rust_object_source.as_ptr() as usize - source.as_ptr() as usize;
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let end = offset + rust_object_source.len();
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(offset, end)
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}
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