use quote! macro to generate grammar

We already use syn&quote elsewhere (transitively), so it make sense to
cut down on the number of technologies and get rid of tera

3 files changed, 180 insertions, 40 deletions

diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index a18810253..26efeeba9 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -263,7 +263,7 @@ Grammar(
         "SourceFile": (
             traits: [ "ModuleItemOwner", "FnDefOwner" ],
             collections: [
-                ["modules", "Module"],
+                ("modules", "Module"),
             ]
         ),
         "FnDef": (
@@ -286,7 +286,7 @@ Grammar(
                 "DocCommentsOwner"
             ]
         ),
-        "NamedFieldDefList": (collections: [["fields", "NamedFieldDef"]]),
+        "NamedFieldDefList": (collections: [("fields", "NamedFieldDef")]),
         "NamedFieldDef": (
             traits: [
                 "VisibilityOwner",
@@ -296,7 +296,7 @@ Grammar(
                 "TypeAscriptionOwner"
             ]
         ),
-        "PosFieldDefList": (collections: [["fields", "PosFieldDef"]]),
+        "PosFieldDefList": (collections: [("fields", "PosFieldDef")]),
         "PosFieldDef": ( traits: ["VisibilityOwner", "AttrsOwner"], options: ["TypeRef"]),
         "EnumDef": ( traits: [
             "VisibilityOwner",
@@ -305,7 +305,7 @@ Grammar(
             "AttrsOwner",
             "DocCommentsOwner"
         ], options: [["variant_list", "EnumVariantList"]] ),
-        "EnumVariantList": ( collections: [["variants", "EnumVariant"]] ),
+        "EnumVariantList": ( collections: [("variants", "EnumVariant")] ),
         "EnumVariant": ( traits: ["NameOwner", "DocCommentsOwner", "AttrsOwner"], options: ["Expr"] ),
         "TraitDef": (
             traits: ["VisibilityOwner", "NameOwner", "AttrsOwner", "DocCommentsOwner", "TypeParamsOwner", "TypeBoundsOwner"],
@@ -316,7 +316,7 @@ Grammar(
             options: [ "ItemList" ]
         ),
         "ItemList": (
-            collections: [["impl_items", "ImplItem"]],
+            collections: [("impl_items", "ImplItem")],
             traits: [ "FnDefOwner", "ModuleItemOwner" ],
         ),
         "ConstDef": (
@@ -355,7 +355,7 @@ Grammar(
         "ImplBlock": (options: ["ItemList"], traits: ["TypeParamsOwner", "AttrsOwner"]),
 
         "ParenType": (options: ["TypeRef"]),
-        "TupleType": ( collections: [["fields", "TypeRef"]] ),
+        "TupleType": ( collections: [("fields", "TypeRef")] ),
         "NeverType": (),
         "PathType": (options: ["Path"]),
         "PointerType": (options: ["TypeRef"]),
@@ -405,10 +405,10 @@ Grammar(
         ),
 
         "TupleExpr": (
-            collections: [["exprs", "Expr"]]
+            collections: [("exprs", "Expr")]
         ),
         "ArrayExpr": (
-            collections: [["exprs", "Expr"]]
+            collections: [("exprs", "Expr")]
         ),
         "ParenExpr": (options: ["Expr"]),
         "PathExpr": (options: ["Path"]),
@@ -449,7 +449,7 @@ Grammar(
             options: [ "Expr", "MatchArmList" ],
         ),
         "MatchArmList": (
-            collections: [ ["arms", "MatchArm"] ],
+            collections: [ ("arms", "MatchArm") ],
             traits: [ "AttrsOwner" ]
         ),
         "MatchArm": (
@@ -457,13 +457,13 @@ Grammar(
                 [ "guard", "MatchGuard" ],
                 "Expr",
             ],
-            collections: [ [ "pats", "Pat" ] ],
+            collections: [ ("pats", "Pat") ],
             traits: [ "AttrsOwner" ]
         ),
         "MatchGuard": (options: ["Expr"]),
         "StructLit": (options: ["Path", "NamedFieldList"]),
         "NamedFieldList": (
-            collections: [ ["fields", "NamedField"] ],
+            collections: [ ("fields", "NamedField") ],
             options: [["spread", "Expr"]]
         ),
         "NamedField": (options: ["NameRef", "Expr"]),
@@ -532,8 +532,8 @@ Grammar(
         "StructPat": ( options: ["FieldPatList", "Path"] ),
         "FieldPatList": (
             collections: [
-                ["field_pats", "FieldPat"],
-                ["bind_pats", "BindPat"],
+                ("field_pats", "FieldPat"),
+                ("bind_pats", "BindPat"),
             ]
         ),
         "FieldPat": (
@@ -542,9 +542,9 @@ Grammar(
         ),
         "TupleStructPat": (
             options: ["Path"],
-            collections: [["args", "Pat"]],
+            collections: [("args", "Pat")],
         ),
-        "TuplePat": ( collections: [["args", "Pat"]] ),
+        "TuplePat": ( collections: [("args", "Pat")] ),
         "SlicePat": (),
         "RangePat": (),
         "LiteralPat": (options: ["Literal"]),
@@ -575,8 +575,8 @@ Grammar(
         "TokenTree": (),
         "TypeParamList": (
             collections: [
-                ["type_params", "TypeParam" ],
-                ["lifetime_params", "LifetimeParam" ],
+                ("type_params", "TypeParam" ),
+                ("lifetime_params", "LifetimeParam" ),
             ]
         ),
         "TypeParam": ( traits: ["NameOwner", "AttrsOwner", "TypeBoundsOwner", "DefaultTypeParamOwner"] ),
@@ -590,7 +590,7 @@ Grammar(
         ),
         "TypeBoundList": (
             collections: [
-                ["bounds", "TypeBound"],
+                ("bounds", "TypeBound"),
             ]
         ),
         "WherePred": (
@@ -603,7 +603,7 @@ Grammar(
         ),
         "WhereClause": (
             collections: [
-                ["predicates", "WherePred"],
+                ("predicates", "WherePred"),
             ],
         ),
         "ExprStmt": (
@@ -627,7 +627,7 @@ Grammar(
         "Block": (
             options: [ "Expr" ],
             collections: [
-                ["statements", "Stmt"],
+                ("statements", "Stmt"),
             ],
             traits: [
                 "AttrsOwner",
@@ -636,7 +636,7 @@ Grammar(
         "ParamList": (
             options: [ "SelfParam" ],
             collections: [
-                ["params", "Param"]
+                ("params", "Param"),
             ]
         ),
         "SelfParam": (
@@ -663,14 +663,14 @@ Grammar(
             traits: ["NameOwner"],
         ),
         "UseTreeList": (
-            collections: [["use_trees", "UseTree"]]
+            collections: [("use_trees", "UseTree")]
         ),
         "ExternCrateItem": (
             options: ["NameRef", "Alias"],
         ),
         "ArgList": (
             collections: [
-                ["args", "Expr"]
+                ("args", "Expr"),
             ]
         ),
         "Path": (
@@ -683,9 +683,9 @@ Grammar(
             options: [ "NameRef", "TypeArgList" ]
         ),
         "TypeArgList": (collections: [
-            ["type_args", "TypeArg"],
-            ["lifetime_args", "LifetimeArg"],
-            ["assoc_type_args", "AssocTypeArg"],
+            ("type_args", "TypeArg"),
+            ("lifetime_args", "LifetimeArg"),
+            ("assoc_type_args", "AssocTypeArg"),
         ]),
         "TypeArg": (options: ["TypeRef"]),
         "AssocTypeArg": (options: ["NameRef", "TypeRef"]),
@@ -698,7 +698,7 @@ Grammar(
         "MacroStmts" : (
             options: [ "Expr" ],
             collections: [
-                ["statements", "Stmt"],
+                ("statements", "Stmt"),
             ],
         )
     },
diff --git a/crates/ra_tools/Cargo.toml b/crates/ra_tools/Cargo.toml
index ab9fa5d86..1bb6fb71c 100644
--- a/crates/ra_tools/Cargo.toml
+++ b/crates/ra_tools/Cargo.toml
@@ -12,4 +12,5 @@ itertools = "0.8.0"
 clap = "2.32.0"
 quote = "1.0.2"
 ron = "0.5.1"
+heck = "0.3.0"
 serde = { version = "1.0.0", features = ["derive"] }
diff --git a/crates/ra_tools/src/codegen.rs b/crates/ra_tools/src/codegen.rs
index f0a54808a..e14092704 100644
--- a/crates/ra_tools/src/codegen.rs
+++ b/crates/ra_tools/src/codegen.rs
@@ -1,27 +1,162 @@
-use std::{collections::BTreeMap, fs, path::Path};
+use std::{
+    collections::BTreeMap,
+    fs,
+    io::Write,
+    path::Path,
+    process::{Command, Stdio},
+};
 
-use quote::quote;
+use heck::{ShoutySnakeCase, SnakeCase};
+use quote::{format_ident, quote};
 use ron;
 use serde::Deserialize;
 
-use crate::{project_root, Mode, Result, AST, GRAMMAR};
+use crate::{project_root, Mode, Result, AST, GRAMMAR, SYNTAX_KINDS};
 
 pub fn generate(mode: Mode) -> Result<()> {
     let grammar = project_root().join(GRAMMAR);
-    // let syntax_kinds = project_root().join(SYNTAX_KINDS);
-    let ast = project_root().join(AST);
-    generate_ast(&grammar, &ast, mode)
-}
-
-fn generate_ast(grammar_src: &Path, dst: &Path, mode: Mode) -> Result<()> {
-    let src: Grammar = {
-        let text = fs::read_to_string(grammar_src)?;
+    let grammar: Grammar = {
+        let text = fs::read_to_string(grammar)?;
         ron::de::from_str(&text)?
     };
-    eprintln!("{:#?}", src);
+
+    let _syntax_kinds = project_root().join(SYNTAX_KINDS);
+    let _ast = project_root().join(AST);
+
+    let ast = generate_ast(&grammar)?;
+    println!("{}", ast);
     Ok(())
 }
 
+fn generate_ast(grammar: &Grammar) -> Result<String> {
+    let nodes = grammar.ast.iter().map(|(name, ast_node)| {
+        let variants =
+            ast_node.variants.iter().map(|var| format_ident!("{}", var)).collect::<Vec<_>>();
+        let name = format_ident!("{}", name);
+
+        let kinds = if variants.is_empty() { vec![name.clone()] } else { variants.clone() }
+            .into_iter()
+            .map(|name| format_ident!("{}", name.to_string().to_shouty_snake_case()))
+            .collect::<Vec<_>>();
+
+        let variants = if variants.is_empty() {
+            None
+        } else {
+            let kind_enum = format_ident!("{}Kind", name);
+            Some(quote!(
+                pub enum #kind_enum {
+                    #(#variants(#variants),)*
+                }
+
+                #(
+                impl From<#variants> for #name {
+                    fn from(node: #variants) -> #name {
+                        #name { syntax: node.syntax }
+                    }
+                }
+                )*
+
+                impl #name {
+                    pub fn kind(&self) -> #kind_enum {
+                        let syntax = self.syntax.clone();
+                        match syntax.kind() {
+                            #(
+                            #kinds =>
+                                #kind_enum::#variants(#variants { syntax }),
+                            )*
+                            _ => unreachable!(),
+                        }
+                    }
+                }
+            ))
+        };
+
+        let traits = ast_node.traits.iter().map(|trait_name| {
+            let trait_name = format_ident!("{}", trait_name);
+            quote!(impl ast::#trait_name for #name {})
+        });
+
+        let collections = ast_node.collections.iter().map(|(name, kind)| {
+            let method_name = format_ident!("{}", name);
+            let kind = format_ident!("{}", kind);
+            quote! {
+                pub fn #method_name(&self) -> AstChildren<#kind> {
+                    AstChildren::new(&self.syntax)
+                }
+            }
+        });
+
+        let options = ast_node.options.iter().map(|attr| {
+            let method_name = match attr {
+                Attr::Type(t) => format_ident!("{}", t.to_snake_case()),
+                Attr::NameType(n, _) => format_ident!("{}", n),
+            };
+            let ty = match attr {
+                Attr::Type(t) | Attr::NameType(_, t) => format_ident!("{}", t),
+            };
+            quote! {
+                pub fn #method_name(&self) -> Option<#ty> {
+                    AstChildren::new(&self.syntax).next()
+                }
+            }
+        });
+
+        quote! {
+            #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+            pub struct #name {
+                pub(crate) syntax: SyntaxNode,
+            }
+
+            impl AstNode for #name {
+                fn can_cast(kind: SyntaxKind) -> bool {
+                    match kind {
+                        #(#kinds)|* => true,
+                        _ => false,
+                    }
+                }
+                fn cast(syntax: SyntaxNode) -> Option<Self> {
+                    if Self::can_cast(syntax.kind()) { Some(Self { syntax }) } else { None }
+                }
+                fn syntax(&self) -> &SyntaxNode { &self.syntax }
+            }
+
+            #variants
+
+            #(#traits)*
+
+            impl #name {
+                #(#collections)*
+                #(#options)*
+            }
+        }
+    });
+
+    let ast = quote! {
+        use crate::{
+            SyntaxNode, SyntaxKind::{self, *},
+            ast::{self, AstNode, AstChildren},
+        };
+
+        #(#nodes)*
+    };
+
+    let pretty = reformat(ast)?;
+    Ok(pretty)
+}
+
+fn reformat(text: impl std::fmt::Display) -> Result<String> {
+    let mut rustfmt = Command::new("rustfmt")
+        .arg("--config-path")
+        .arg(project_root().join("rustfmt.toml"))
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .spawn()?;
+    write!(rustfmt.stdin.take().unwrap(), "{}", text)?;
+    let output = rustfmt.wait_with_output()?;
+    let stdout = String::from_utf8(output.stdout)?;
+    Ok(stdout)
+}
+
 #[derive(Deserialize, Debug)]
 struct Grammar {
     single_byte_tokens: Vec<(String, String)>,
@@ -36,9 +171,13 @@ struct Grammar {
 #[derive(Deserialize, Debug)]
 struct AstNode {
     #[serde(default)]
+    #[serde(rename = "enum")]
+    variants: Vec<String>,
+
+    #[serde(default)]
     traits: Vec<String>,
     #[serde(default)]
-    collections: Vec<Attr>,
+    collections: Vec<(String, String)>,
     #[serde(default)]
     options: Vec<Attr>,
 }