Merge pull request #3890 from sei40kr/feat/rust-location-methods

[rust] add `Location` line/column and chop methods

Author: kddnewton

include/prism/util/pm_line_offset_list.h

@@ -96,7 +96,7 @@ int32_t pm_line_offset_list_line(const pm_line_offset_list_t *list, uint32_t cur
  * @param start_line The line to start counting from.
  * @return The line and column of the given offset.
  */
-pm_line_column_t pm_line_offset_list_line_column(const pm_line_offset_list_t *list, uint32_t cursor, int32_t start_line);
+PRISM_EXPORTED_FUNCTION pm_line_column_t pm_line_offset_list_line_column(const pm_line_offset_list_t *list, uint32_t cursor, int32_t start_line);
 
 /**
  * Free the internal memory allocated for the list.

rust/ruby-prism-sys/build/main.rs

@@ -9,6 +9,7 @@ fn main() {
 
     let ruby_build_path = prism_lib_path();
     let ruby_include_path = prism_include_path();
+    emit_rerun_hints(&ruby_include_path);
 
     // Tell cargo/rustc that we want to link against `libprism.a`.
     println!("cargo:rustc-link-lib=static=prism");
@@ -23,6 +24,19 @@ fn main() {
     write_bindings(&bindings);
 }
 
+fn emit_rerun_hints(ruby_include_path: &Path) {
+    println!("cargo:rerun-if-env-changed=PRISM_INCLUDE_DIR");
+    println!("cargo:rerun-if-env-changed=PRISM_LIB_DIR");
+    println!("cargo:rerun-if-changed={}", ruby_include_path.display());
+
+    if let Some(project_root) = ruby_include_path.parent() {
+        let src_path = project_root.join("src");
+        if src_path.exists() {
+            println!("cargo:rerun-if-changed={}", src_path.display());
+        }
+    }
+}
+
 /// Gets the path to project files (`libprism*`) at `[root]/build/`.
 ///
 fn prism_lib_path() -> PathBuf {
@@ -134,6 +148,7 @@ fn generate_bindings(ruby_include_path: &Path) -> bindgen::Bindings {
         .rustified_non_exhaustive_enum("pm_options_version_t")
         // Functions
         .allowlist_function("pm_arena_free")
+        .allowlist_function("pm_line_offset_list_line_column")
         .allowlist_function("pm_list_empty_p")
         .allowlist_function("pm_list_free")
         .allowlist_function("pm_options_command_line_set")

rust/ruby-prism/src/lib.rs

@@ -448,7 +448,7 @@ mod tests {
     }
 
     #[test]
-    fn location_test() {
+    fn location_slice_test() {
         let source = "111 + 222 + 333";
         let result = parse(source.as_ref());
 
@@ -502,6 +502,48 @@ mod tests {
         assert_eq!(slice, "222");
     }
 
+    #[test]
+    fn location_line_column_test() {
+        let source = "first\nsecond\nthird";
+        let result = parse(source.as_ref());
+
+        let node = result.node();
+        let program = node.as_program_node().unwrap();
+        let statements = program.statements().body();
+        let mut iter = statements.iter();
+
+        let _first = iter.next().unwrap();
+        let second = iter.next().unwrap();
+        let third = iter.next().unwrap();
+
+        let second_loc = second.location();
+        assert_eq!(second_loc.start_line(), 2);
+        assert_eq!(second_loc.end_line(), 2);
+        assert_eq!(second_loc.start_column(), 0);
+        assert_eq!(second_loc.end_column(), 6);
+
+        let third_loc = third.location();
+        assert_eq!(third_loc.start_line(), 3);
+        assert_eq!(third_loc.end_line(), 3);
+        assert_eq!(third_loc.start_column(), 0);
+        assert_eq!(third_loc.end_column(), 5);
+    }
+
+    #[test]
+    fn location_chop_test() {
+        let result = parse(b"foo");
+        let mut location = result.node().as_program_node().unwrap().location();
+
+        assert_eq!(location.chop().as_slice(), b"fo");
+        assert_eq!(location.chop().chop().chop().as_slice(), b"");
+
+        // Check that we don't go negative.
+        for _ in 0..10 {
+            location = location.chop();
+        }
+        assert_eq!(location.as_slice(), b"");
+    }
+
     #[test]
     fn visitor_test() {
         use super::{visit_interpolated_regular_expression_node, visit_regular_expression_node, InterpolatedRegularExpressionNode, RegularExpressionNode, Visit};

rust/ruby-prism/src/parse_result/mod.rs

@@ -8,7 +8,7 @@ mod diagnostics;
 
 use std::ptr::NonNull;
 
-use ruby_prism_sys::{pm_arena_free, pm_arena_t, pm_comment_t, pm_diagnostic_t, pm_location_t, pm_magic_comment_t, pm_node_t, pm_parser_free, pm_parser_t};
+use ruby_prism_sys::{pm_arena_free, pm_arena_t, pm_comment_t, pm_diagnostic_t, pm_line_offset_list_line_column, pm_location_t, pm_magic_comment_t, pm_node_t, pm_parser_free, pm_parser_t};
 
 pub use self::comments::{Comment, CommentType, Comments, MagicComment, MagicComments};
 pub use self::diagnostics::{Diagnostic, Diagnostics};
@@ -66,6 +66,56 @@ impl<'pr> Location<'pr> {
             })
         }
     }
+
+    /// Returns a new location that is the result of chopping off the last byte.
+    #[must_use]
+    pub const fn chop(&self) -> Self {
+        Location {
+            parser: self.parser,
+            start: self.start,
+            length: if self.length == 0 { 0 } else { self.length - 1 },
+            marker: std::marker::PhantomData,
+        }
+    }
+}
+
+impl Location<'_> {
+    /// Returns the line number where this location starts.
+    #[must_use]
+    pub fn start_line(&self) -> i32 {
+        self.line_column(self.start).0
+    }
+
+    /// Returns the column number in bytes where this location starts from the
+    /// start of the line.
+    #[must_use]
+    pub fn start_column(&self) -> u32 {
+        self.line_column(self.start).1
+    }
+
+    /// Returns the line number where this location ends.
+    #[must_use]
+    pub fn end_line(&self) -> i32 {
+        self.line_column(self.end()).0
+    }
+
+    /// Returns the column number in bytes where this location ends from the
+    /// start of the line.
+    #[must_use]
+    pub fn end_column(&self) -> u32 {
+        self.line_column(self.end()).1
+    }
+
+    /// Returns the line and column number for the given byte offset.
+    fn line_column(&self, cursor: u32) -> (i32, u32) {
+        // SAFETY: We read the line_offsets and start_line from the parser,
+        // which is valid for the lifetime of this Location.
+        unsafe {
+            let parser = self.parser.as_ptr();
+            let result = pm_line_offset_list_line_column(&raw const (*parser).line_offsets, cursor, (*parser).start_line);
+            (result.line, result.column)
+        }
+    }
 }
 
 impl std::fmt::Debug for Location<'_> {