1 files changed, 51 insertions, 0 deletions

diff --git a/crates/project_model/src/cfg_flag.rs b/crates/project_model/src/cfg_flag.rs
new file mode 100644
index 000000000..e92962cf6
--- /dev/null
+++ b/crates/project_model/src/cfg_flag.rs
@@ -0,0 +1,51 @@
+//! Parsing of CfgFlags as command line arguments, as in
+//!
+//! rustc main.rs --cfg foo --cfg 'feature="bar"'
+use std::str::FromStr;
+
+use cfg::CfgOptions;
+use stdx::split_once;
+
+#[derive(Clone, Eq, PartialEq, Debug)]
+pub enum CfgFlag {
+    Atom(String),
+    KeyValue { key: String, value: String },
+}
+
+impl FromStr for CfgFlag {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let res = match split_once(s, '=') {
+            Some((key, value)) => {
+                if !(value.starts_with('"') && value.ends_with('"')) {
+                    return Err(format!("Invalid cfg ({:?}), value should be in quotes", s));
+                }
+                let key = key.to_string();
+                let value = value[1..value.len() - 1].to_string();
+                CfgFlag::KeyValue { key, value }
+            }
+            None => CfgFlag::Atom(s.into()),
+        };
+        Ok(res)
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for CfgFlag {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        String::deserialize(deserializer)?.parse().map_err(serde::de::Error::custom)
+    }
+}
+
+impl Extend<CfgFlag> for CfgOptions {
+    fn extend<T: IntoIterator<Item = CfgFlag>>(&mut self, iter: T) {
+        for cfg_flag in iter {
+            match cfg_flag {
+                CfgFlag::Atom(it) => self.insert_atom(it.into()),
+                CfgFlag::KeyValue { key, value } => self.insert_key_value(key.into(), value.into()),
+            }
+        }
+    }
+}