2 files changed, 131 insertions, 20 deletions

diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index 71a57fba2..988853ed2 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -1,31 +1,13 @@
 //! Missing batteries for standard libraries.
-
 use std::{cell::Cell, fmt, time::Instant};
 
+mod macros;
+
 #[inline(always)]
 pub fn is_ci() -> bool {
     option_env!("CI").is_some()
 }
 
-#[macro_export]
-macro_rules! eprintln {
-    ($($tt:tt)*) => {{
-        if $crate::is_ci() {
-            panic!("Forgot to remove debug-print?")
-        }
-        std::eprintln!($($tt)*)
-    }}
-}
-
-/// Appends formatted string to a `String`.
-#[macro_export]
-macro_rules! format_to {
-    ($buf:expr) => ();
-    ($buf:expr, $lit:literal $($arg:tt)*) => {
-        { use ::std::fmt::Write as _; let _ = ::std::write!($buf, $lit $($arg)*); }
-    };
-}
-
 pub trait SepBy: Sized {
     /// Returns an `impl fmt::Display`, which joins elements via a separator.
     fn sep_by<'a>(self, sep: &'a str) -> SepByBuilder<'a, Self>;
@@ -88,6 +70,8 @@ where
         Ok(())
     }
 }
+
+#[must_use]
 pub fn timeit(label: &'static str) -> impl Drop {
     struct Guard {
         label: &'static str,
@@ -124,3 +108,90 @@ pub fn replace(buf: &mut String, from: char, to: &str) {
     // FIXME: do this in place.
     *buf = buf.replace(from, to)
 }
+
+pub fn split_delim(haystack: &str, delim: char) -> Option<(&str, &str)> {
+    let idx = haystack.find(delim)?;
+    Some((&haystack[..idx], &haystack[idx + delim.len_utf8()..]))
+}
+
+pub fn trim_indent(mut text: &str) -> String {
+    if text.starts_with('\n') {
+        text = &text[1..];
+    }
+    let indent = text
+        .lines()
+        .filter(|it| !it.trim().is_empty())
+        .map(|it| it.len() - it.trim_start().len())
+        .min()
+        .unwrap_or(0);
+    lines_with_ends(text)
+        .map(
+            |line| {
+                if line.len() <= indent {
+                    line.trim_start_matches(' ')
+                } else {
+                    &line[indent..]
+                }
+            },
+        )
+        .collect()
+}
+
+pub fn lines_with_ends(text: &str) -> LinesWithEnds {
+    LinesWithEnds { text }
+}
+
+pub struct LinesWithEnds<'a> {
+    text: &'a str,
+}
+
+impl<'a> Iterator for LinesWithEnds<'a> {
+    type Item = &'a str;
+    fn next(&mut self) -> Option<&'a str> {
+        if self.text.is_empty() {
+            return None;
+        }
+        let idx = self.text.find('\n').map_or(self.text.len(), |it| it + 1);
+        let (res, next) = self.text.split_at(idx);
+        self.text = next;
+        Some(res)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_trim_indent() {
+        assert_eq!(trim_indent(""), "");
+        assert_eq!(
+            trim_indent(
+                "
+            hello
+            world
+"
+            ),
+            "hello\nworld\n"
+        );
+        assert_eq!(
+            trim_indent(
+                "
+            hello
+            world"
+            ),
+            "hello\nworld"
+        );
+        assert_eq!(trim_indent("    hello\n    world\n"), "hello\nworld\n");
+        assert_eq!(
+            trim_indent(
+                "
+            fn main() {
+                return 92;
+            }
+        "
+            ),
+            "fn main() {\n    return 92;\n}\n"
+        );
+    }
+}
diff --git a/crates/stdx/src/macros.rs b/crates/stdx/src/macros.rs
new file mode 100644
index 000000000..bf298460f
--- /dev/null
+++ b/crates/stdx/src/macros.rs
@@ -0,0 +1,40 @@
+//! Convenience macros.
+#[macro_export]
+macro_rules! eprintln {
+    ($($tt:tt)*) => {{
+        if $crate::is_ci() {
+            panic!("Forgot to remove debug-print?")
+        }
+        std::eprintln!($($tt)*)
+    }}
+}
+
+/// Appends formatted string to a `String`.
+#[macro_export]
+macro_rules! format_to {
+    ($buf:expr) => ();
+    ($buf:expr, $lit:literal $($arg:tt)*) => {
+        { use ::std::fmt::Write as _; let _ = ::std::write!($buf, $lit $($arg)*); }
+    };
+}
+
+// Generates `From` impls for `Enum E { Foo(Foo), Bar(Bar) }` enums
+#[macro_export]
+macro_rules! impl_from {
+    ($($variant:ident $(($($sub_variant:ident),*))?),* for $enum:ident) => {
+        $(
+            impl From<$variant> for $enum {
+                fn from(it: $variant) -> $enum {
+                    $enum::$variant(it)
+                }
+            }
+            $($(
+                impl From<$sub_variant> for $enum {
+                    fn from(it: $sub_variant) -> $enum {
+                        $enum::$variant($variant::$sub_variant(it))
+                    }
+                }
+            )*)?
+        )*
+    }
+}