Move FunctionSignature to display/function_signature

1 files changed, 101 insertions, 0 deletions

diff --git a/crates/ra_ide_api/src/display/function_signature.rs b/crates/ra_ide_api/src/display/function_signature.rs
new file mode 100644
index 000000000..d09950bce
--- /dev/null
+++ b/crates/ra_ide_api/src/display/function_signature.rs
@@ -0,0 +1,101 @@
+use super::{where_predicates, generic_parameters};
+use crate::db;
+use std::fmt::{self, Display};
+use join_to_string::join;
+use ra_syntax::ast::{self, AstNode, NameOwner, VisibilityOwner};
+use std::convert::From;
+use hir::{Docs, Documentation};
+
+/// Contains information about a function signature
+#[derive(Debug)]
+pub struct FunctionSignature {
+    /// Optional visibility
+    pub visibility: Option<String>,
+    /// Name of the function
+    pub name: Option<String>,
+    /// Documentation for the function
+    pub doc: Option<Documentation>,
+    /// Generic parameters
+    pub generic_parameters: Vec<String>,
+    /// Parameters of the function
+    pub parameters: Vec<String>,
+    /// Optional return type
+    pub ret_type: Option<String>,
+    /// Where predicates
+    pub where_predicates: Vec<String>,
+}
+
+impl FunctionSignature {
+    pub(crate) fn with_doc_opt(mut self, doc: Option<Documentation>) -> Self {
+        self.doc = doc;
+        self
+    }
+
+    pub(crate) fn from_hir(db: &db::RootDatabase, function: hir::Function) -> Self {
+        let doc = function.docs(db);
+        let (_, ast_node) = function.source(db);
+        FunctionSignature::from(&*ast_node).with_doc_opt(doc)
+    }
+}
+
+impl From<&'_ ast::FnDef> for FunctionSignature {
+    fn from(node: &ast::FnDef) -> FunctionSignature {
+        fn param_list(node: &ast::FnDef) -> Vec<String> {
+            let mut res = vec![];
+            if let Some(param_list) = node.param_list() {
+                if let Some(self_param) = param_list.self_param() {
+                    res.push(self_param.syntax().text().to_string())
+                }
+
+                res.extend(param_list.params().map(|param| param.syntax().text().to_string()));
+            }
+            res
+        }
+
+        FunctionSignature {
+            visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+            name: node.name().map(|n| n.text().to_string()),
+            ret_type: node
+                .ret_type()
+                .and_then(|r| r.type_ref())
+                .map(|n| n.syntax().text().to_string()),
+            parameters: param_list(node),
+            generic_parameters: generic_parameters(node),
+            where_predicates: where_predicates(node),
+            // docs are processed separately
+            doc: None,
+        }
+    }
+}
+
+impl Display for FunctionSignature {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(t) = &self.visibility {
+            write!(f, "{} ", t)?;
+        }
+
+        if let Some(name) = &self.name {
+            write!(f, "fn {}", name)?;
+        }
+
+        if !self.generic_parameters.is_empty() {
+            join(self.generic_parameters.iter())
+                .separator(", ")
+                .surround_with("<", ">")
+                .to_fmt(f)?;
+        }
+
+        join(self.parameters.iter()).separator(", ").surround_with("(", ")").to_fmt(f)?;
+
+        if let Some(t) = &self.ret_type {
+            write!(f, " -> {}", t)?;
+        }
+
+        if !self.where_predicates.is_empty() {
+            write!(f, "\nwhere ")?;
+            join(self.where_predicates.iter()).separator(",\n      ").to_fmt(f)?;
+        }
+
+        Ok(())
+    }
+}