aboutsummaryrefslogtreecommitdiffstats
path: root/askama_derive/src/generator.rs
diff options
context:
space:
mode:
Diffstat (limited to 'askama_derive/src/generator.rs')
-rw-r--r--askama_derive/src/generator.rs918
1 files changed, 918 insertions, 0 deletions
diff --git a/askama_derive/src/generator.rs b/askama_derive/src/generator.rs
new file mode 100644
index 0000000..357bd0f
--- /dev/null
+++ b/askama_derive/src/generator.rs
@@ -0,0 +1,918 @@
+use input::TemplateInput;
+use parser::{self, Cond, Expr, Macro, MatchParameter, MatchVariant, Node, Target, When, WS};
+use shared::{filters, path};
+
+use quote::{ToTokens, Tokens};
+
+use std::{cmp, hash, str};
+use std::path::Path;
+use std::collections::{HashMap, HashSet};
+
+use syn;
+
+
+pub fn generate(input: &TemplateInput, nodes: &[Node], imported: &HashMap<(&str, &str), Macro>)
+ -> String {
+ Generator::default().build(&State::new(input, nodes, imported))
+}
+
+struct State<'a> {
+ input: &'a TemplateInput<'a>,
+ nodes: &'a [Node<'a>],
+ blocks: Vec<&'a Node<'a>>,
+ macros: MacroMap<'a>,
+ trait_name: String,
+ derived: bool,
+}
+
+impl<'a> State<'a> {
+ fn new<'n>(input: &'n TemplateInput, nodes: &'n [Node], imported:
+ &'n HashMap<(&'n str, &'n str), Macro<'n>>) -> State<'n> {
+ let mut base: Option<&Expr> = None;
+ let mut blocks = Vec::new();
+ let mut macros = HashMap::new();
+ for n in nodes.iter() {
+ match *n {
+ Node::Extends(ref path) => match base {
+ Some(_) => panic!("multiple extend blocks found"),
+ None => {
+ base = Some(path);
+ },
+ },
+ ref def @ Node::BlockDef(_, _, _, _) => {
+ blocks.push(def);
+ },
+ Node::Macro(name, ref m) => {
+ macros.insert((None, name), m);
+ },
+ _ => {},
+ }
+ }
+ for (&(scope, name), m) in imported {
+ macros.insert((Some(scope), name), m);
+ }
+ State {
+ input,
+ nodes,
+ blocks,
+ macros,
+ trait_name: trait_name_for_path(&base, &input.path),
+ derived: base.is_some(),
+ }
+ }
+}
+
+fn trait_name_for_path(base: &Option<&Expr>, path: &Path) -> String {
+ let rooted_path = match *base {
+ Some(&Expr::StrLit(user_path)) => path::find_template_from_path(user_path, Some(path)),
+ _ => path.to_path_buf(),
+ };
+
+ let mut res = String::new();
+ res.push_str("TraitFrom");
+ for c in rooted_path.to_string_lossy().chars() {
+ if c.is_alphanumeric() {
+ res.push(c);
+ } else {
+ res.push_str(&format!("{:x}", c as u32));
+ }
+ }
+ res
+}
+
+fn get_parent_type(ast: &syn::DeriveInput) -> Option<&syn::Type> {
+ match ast.data {
+ syn::Data::Struct(syn::DataStruct {
+ fields: syn::Fields::Named(ref fields),
+ ..
+ }) => fields.named.iter().filter_map(|f| {
+ f.ident.as_ref().and_then(|name| {
+ if name.as_ref() == "_parent" {
+ Some(&f.ty)
+ } else {
+ None
+ }
+ })
+ }),
+ _ => panic!("derive(Template) only works for struct items"),
+ }.next()
+}
+
+struct Generator<'a> {
+ buf: String,
+ indent: u8,
+ start: bool,
+ locals: SetChain<'a, &'a str>,
+ next_ws: Option<&'a str>,
+ skip_ws: bool,
+}
+
+impl<'a> Generator<'a> {
+ fn new<'n>(locals: SetChain<'n, &'n str>, indent: u8) -> Generator<'n> {
+ Generator {
+ buf: String::new(),
+ indent: indent,
+ start: true,
+ locals: locals,
+ next_ws: None,
+ skip_ws: false,
+ }
+ }
+
+ fn default<'n>() -> Generator<'n> {
+ Self::new(SetChain::new(), 0)
+ }
+
+ fn child(&mut self) -> Generator {
+ let locals = SetChain::with_parent(&self.locals);
+ Self::new(locals, self.indent)
+ }
+
+ // Takes a State and generates the relevant implementations.
+ fn build(mut self, state: &'a State) -> String {
+ if !state.blocks.is_empty() {
+ if !state.derived {
+ self.define_trait(state);
+ } else {
+ let parent_type = get_parent_type(state.input.ast)
+ .expect("expected field '_parent' in extending template struct");
+ self.deref_to_parent(state, parent_type);
+ }
+
+ let trait_nodes = if !state.derived {
+ Some(&state.nodes[..])
+ } else {
+ None
+ };
+ self.impl_trait(state, trait_nodes);
+ self.impl_template_for_trait(state);
+ } else {
+ self.impl_template(state);
+ }
+ self.impl_display(state);
+ if cfg!(feature = "iron") {
+ self.impl_modifier_response(state);
+ }
+ if cfg!(feature = "rocket") {
+ self.impl_responder(state);
+ }
+ self.buf
+ }
+
+ // Implement `Template` for the given context struct.
+ fn impl_template(&mut self, state: &'a State) {
+ self.write_header(state, "::askama::Template", &[]);
+ self.writeln("fn render_into(&self, writer: &mut ::std::fmt::Write) -> \
+ ::askama::Result<()> {");
+ self.writeln("#[allow(unused_imports)] use ::std::ops::Deref as HiddenDerefTrait;");
+ self.handle(state, state.nodes, AstLevel::Top);
+ self.flush_ws(&WS(false, false));
+ self.writeln("Ok(())");
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Implement `Display` for the given context struct.
+ fn impl_display(&mut self, state: &'a State) {
+ self.write_header(state, "::std::fmt::Display", &[]);
+ self.writeln("fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {");
+ self.writeln("self.render_into(f).map_err(|_| ::std::fmt::Error {})");
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Implement `Deref<Parent>` for an inheriting context struct.
+ fn deref_to_parent(&mut self, state: &'a State, parent_type: &syn::Type) {
+ self.write_header(state, "::std::ops::Deref", &[]);
+ let mut tokens = Tokens::new();
+ parent_type.to_tokens(&mut tokens);
+ self.writeln(&format!("type Target = {};", tokens));
+ self.writeln("fn deref(&self) -> &Self::Target {");
+ self.writeln("&self._parent");
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Implement `TraitFromPathName` for the given context struct.
+ fn impl_trait(&mut self, state: &'a State, nodes: Option<&'a [Node]>) {
+ self.write_header(state, &state.trait_name, &[]);
+ self.write_block_defs(state);
+
+ self.writeln("#[allow(unused_variables)]");
+ self.writeln(&format!(
+ "fn render_trait_into(&self, timpl: &{}, writer: &mut ::std::fmt::Write) \
+ -> ::askama::Result<()> {{",
+ state.trait_name
+ ));
+ self.writeln("#[allow(unused_imports)] use ::std::ops::Deref as HiddenDerefTrait;");
+
+ if let Some(nodes) = nodes {
+ self.handle(state, nodes, AstLevel::Top);
+ self.flush_ws(&WS(false, false));
+ } else {
+ self.writeln("self._parent.render_trait_into(self, writer)?;");
+ }
+
+ self.writeln("Ok(())");
+ self.writeln("}");
+ self.flush_ws(&WS(false, false));
+ self.writeln("}");
+ }
+
+ // Implement `Template` for templates that implement a template trait.
+ fn impl_template_for_trait(&mut self, state: &'a State) {
+ self.write_header(state, "::askama::Template", &[]);
+ self.writeln("fn render_into(&self, writer: &mut ::std::fmt::Write) \
+ -> ::askama::Result<()> {");
+ if state.derived {
+ self.writeln("self._parent.render_trait_into(self, writer)?;");
+ } else {
+ self.writeln("self.render_trait_into(self, writer)?;");
+ }
+ self.writeln("Ok(())");
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Defines the `TraitFromPathName` trait.
+ fn define_trait(&mut self, state: &'a State) {
+ self.writeln(&format!("pub trait {} {{", state.trait_name));
+ self.write_block_defs(state);
+ self.writeln(&format!(
+ "fn render_trait_into(&self, timpl: &{}, writer: &mut ::std::fmt::Write) \
+ -> ::askama::Result<()>;",
+ state.trait_name));
+ self.writeln("}");
+ }
+
+ // Implement iron's Modifier<Response> if enabled
+ fn impl_modifier_response(&mut self, state: &'a State) {
+ self.write_header(state, "::askama::iron::Modifier<::askama::iron::Response>", &[]);
+ self.writeln("fn modify(self, res: &mut ::askama::iron::Response) {");
+ self.writeln("res.body = Some(Box::new(self.render().unwrap().into_bytes()));");
+
+ let ext = state.input.path.extension().map_or("", |s| s.to_str().unwrap_or(""));
+ match ext {
+ "html" | "htm" => {
+ self.writeln("::askama::iron::ContentType::html().0.modify(res);");
+ },
+ _ => (),
+ };
+
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Implement Rocket's `Responder`.
+ fn impl_responder(&mut self, state: &'a State) {
+ self.write_header(state, "::askama::rocket::Responder<'r>", &[quote!('r)]);
+ self.writeln("fn respond_to(self, _: &::askama::rocket::Request) \
+ -> ::askama::rocket::Result<'r> {");
+
+ let ext = match state.input.path.extension() {
+ Some(s) => s.to_str().unwrap(),
+ None => "txt",
+ };
+ self.writeln(&format!("::askama::rocket::respond(&self, {:?})", ext));
+
+ self.writeln("}");
+ self.writeln("}");
+ }
+
+ // Writes header for the `impl` for `TraitFromPathName` or `Template`
+ // for the given context struct.
+ fn write_header(&mut self, state: &'a State, target: &str, vars: &[Tokens]) {
+ let mut generics = state.input.ast.generics.clone();
+ for v in vars.iter() {
+ generics.params.push(parse_quote!(#v));
+ }
+ let (_, orig_ty_generics, _) = state.input.ast.generics.split_for_impl();
+ let (impl_generics, _, where_clause) = generics.split_for_impl();
+ let ident = state.input.ast.ident.as_ref();
+ self.writeln(
+ format!(
+ "{} {} for {}{} {{",
+ quote!(impl#impl_generics),
+ target,
+ ident,
+ quote!(#orig_ty_generics #where_clause),
+ ).as_ref(),
+ );
+ }
+
+ /* Helper methods for handling node types */
+
+ fn handle(&mut self, state: &'a State, nodes: &'a [Node], level: AstLevel) {
+ for n in nodes {
+ match *n {
+ Node::Lit(lws, val, rws) => {
+ self.write_lit(lws, val, rws);
+ },
+ Node::Comment() => {},
+ Node::Expr(ref ws, ref val) => {
+ self.write_expr(state, ws, val);
+ },
+ Node::LetDecl(ref ws, ref var) => {
+ self.write_let_decl(ws, var);
+ },
+ Node::Let(ref ws, ref var, ref val) => {
+ self.write_let(ws, var, val);
+ },
+ Node::Cond(ref conds, ref ws) => {
+ self.write_cond(state, conds, ws);
+ },
+ Node::Match(ref ws1, ref expr, inter, ref arms, ref ws2) => {
+ self.write_match(state, ws1, expr, inter, arms, ws2);
+ },
+ Node::Loop(ref ws1, ref var, ref iter, ref body, ref ws2) => {
+ self.write_loop(state, ws1, var, iter, body, ws2);
+ },
+ Node::BlockDef(ref ws1, name, _, ref ws2) => {
+ if let AstLevel::Nested = level {
+ panic!("blocks ('{}') are only allowed at the top level", name);
+ }
+ self.write_block(ws1, name, ws2);
+ },
+ Node::Include(ref ws, path) => {
+ self.handle_include(state, ws, path);
+ },
+ Node::Call(ref ws, scope, name, ref args) => {
+ self.write_call(state, ws, scope, name, args);
+ },
+ Node::Macro(_, ref m) => {
+ if let AstLevel::Nested = level {
+ panic!("macro blocks only allowed at the top level");
+ }
+ self.flush_ws(&m.ws1);
+ self.prepare_ws(&m.ws2);
+ },
+ Node::Import(ref ws, _, _) => {
+ if let AstLevel::Nested = level {
+ panic!("import blocks only allowed at the top level");
+ }
+ self.handle_ws(ws);
+ },
+ Node::Extends(_) => {
+ if let AstLevel::Nested = level {
+ panic!("extend blocks only allowed at the top level");
+ }
+ // No whitespace handling: child template top-level is not used,
+ // except for the blocks defined in it.
+ },
+ }
+ }
+ }
+
+ fn write_block_defs(&mut self, state: &'a State) {
+ for b in &state.blocks {
+ if let Node::BlockDef(ref ws1, name, ref nodes, ref ws2) = **b {
+ self.writeln("#[allow(unused_variables)]");
+ self.writeln(&format!(
+ "fn render_block_{}_into(&self, writer: &mut ::std::fmt::Write) \
+ -> ::askama::Result<()> {{",
+ name
+ ));
+ self.prepare_ws(ws1);
+
+ self.locals.push();
+ self.handle(state, nodes, AstLevel::Nested);
+ self.locals.pop();
+
+ self.flush_ws(ws2);
+ self.writeln("Ok(())");
+ self.writeln("}");
+ } else {
+ panic!("only block definitions allowed here");
+ }
+ }
+ }
+
+ fn write_cond(&mut self, state: &'a State, conds: &'a [Cond], ws: &WS) {
+ for (i, &(ref cws, ref cond, ref nodes)) in conds.iter().enumerate() {
+ self.handle_ws(cws);
+ match *cond {
+ Some(ref expr) => {
+ if i == 0 {
+ self.write("if ");
+ } else {
+ self.dedent();
+ self.write("} else if ");
+ }
+ self.visit_expr(expr);
+ },
+ None => {
+ self.dedent();
+ self.write("} else");
+ },
+ }
+ self.writeln(" {");
+ self.locals.push();
+ self.handle(state, nodes, AstLevel::Nested);
+ self.locals.pop();
+ }
+ self.handle_ws(ws);
+ self.writeln("}");
+ }
+
+ fn write_match(&mut self, state: &'a State, ws1: &WS, expr: &Expr, inter: Option<&'a str>,
+ arms: &'a [When], ws2: &WS) {
+ self.flush_ws(ws1);
+ if let Some(inter) = inter {
+ if !inter.is_empty() {
+ self.next_ws = Some(inter);
+ }
+ }
+
+ self.write("match ");
+ self.write("(&");
+ self.visit_expr(expr);
+ self.write(").deref()");
+ self.writeln(" {");
+
+ for arm in arms {
+ let &(ref ws, ref variant, ref params, ref body) = arm;
+ self.locals.push();
+ match *variant {
+ Some(ref param) => {
+ self.visit_match_variant(param);
+ },
+ None => self.write("_"),
+ };
+ if !params.is_empty() {
+ self.write("(");
+ for (i, param) in params.iter().enumerate() {
+ if let MatchParameter::Name(p) = *param {
+ self.locals.insert(p);
+ }
+ if i > 0 {
+ self.write(", ");
+ }
+ self.visit_match_param(param);
+ }
+ self.write(")");
+ }
+ self.writeln(" => {");
+ self.handle_ws(ws);
+ self.handle(state, body, AstLevel::Nested);
+ self.writeln("}");
+ self.locals.pop();
+ }
+
+ self.writeln("}");
+ self.handle_ws(ws2);
+ }
+
+ fn write_loop(&mut self, state: &'a State, ws1: &WS, var: &'a Target, iter: &Expr,
+ body: &'a [Node], ws2: &WS) {
+ self.handle_ws(ws1);
+ self.locals.push();
+ self.write("for (_loop_index, ");
+ let targets = self.visit_target(var);
+ for name in &targets {
+ self.locals.insert(name);
+ self.write(name);
+ }
+ self.write(") in (&");
+ self.visit_expr(iter);
+ self.writeln(").into_iter().enumerate() {");
+
+ self.handle(state, body, AstLevel::Nested);
+ self.handle_ws(ws2);
+ self.writeln("}");
+ self.locals.pop();
+ }
+
+ fn write_call(&mut self, state: &'a State, ws: &WS, scope: Option<&str>, name: &str,
+ args: &[Expr]) {
+ let def = state.macros.get(&(scope, name)).unwrap_or_else(|| {
+ if let Some(s) = scope {
+ panic!(format!("macro '{}::{}' not found", s, name));
+ } else {
+ panic!(format!("macro '{}' not found", name));
+ }
+ });
+
+ self.flush_ws(ws); // Cannot handle_ws() here: whitespace from macro definition comes first
+ self.locals.push();
+ self.writeln("{");
+ self.prepare_ws(&def.ws1);
+
+ for (i, arg) in def.args.iter().enumerate() {
+ self.write(&format!("let {} = &", arg));
+ self.visit_expr(args.get(i)
+ .expect(&format!("macro '{}' takes more than {} arguments", name, i)));
+ self.writeln(";");
+ self.locals.insert(arg);
+ }
+ self.handle(state, &def.nodes, AstLevel::Nested);
+
+ self.flush_ws(&def.ws2);
+ self.writeln("}");
+ self.locals.pop();
+ self.prepare_ws(ws);
+ }
+
+ fn handle_include(&mut self, state: &'a State, ws: &WS, path: &str) {
+ self.flush_ws(ws);
+ let path = path::find_template_from_path(path, Some(&state.input.path));
+ let src = path::get_template_source(&path);
+ let nodes = parser::parse(&src);
+ let nested = {
+ let mut gen = self.child();
+ gen.handle(state, &nodes, AstLevel::Nested);
+ gen.buf
+ };
+ self.buf.push_str(&nested);
+ self.prepare_ws(ws);
+ }
+
+ fn write_let_decl(&mut self, ws: &WS, var: &'a Target) {
+ self.handle_ws(ws);
+ self.write("let ");
+ match *var {
+ Target::Name(name) => {
+ self.locals.insert(name);
+ self.write(name);
+ },
+ }
+ self.writeln(";");
+ }
+
+ fn write_let(&mut self, ws: &WS, var: &'a Target, val: &Expr) {
+ self.handle_ws(ws);
+ match *var {
+ Target::Name(name) => {
+ if !self.locals.contains(name) {
+ self.write("let ");
+ self.locals.insert(name);
+ }
+ self.write(name);
+ },
+ }
+ self.write(" = ");
+ self.visit_expr(val);
+ self.writeln(";");
+ }
+
+ fn write_block(&mut self, ws1: &WS, name: &str, ws2: &WS) {
+ self.flush_ws(ws1);
+ self.writeln(&format!("timpl.render_block_{}_into(writer)?;", name));
+ self.prepare_ws(ws2);
+ }
+
+ fn write_expr(&mut self, state: &'a State, ws: &WS, s: &Expr) {
+ self.handle_ws(ws);
+ self.write("let askama_expr = &");
+ let wrapped = self.visit_expr(s);
+ self.writeln(";");
+
+ use self::DisplayWrap::*;
+ use super::input::EscapeMode::*;
+ self.write("writer.write_fmt(format_args!(\"{}\", ");
+ self.write(match (wrapped, &state.input.meta.escaping) {
+ (Wrapped, &Html) |
+ (Wrapped, &None) |
+ (Unwrapped, &None) => "askama_expr",
+ (Unwrapped, &Html) => "&::askama::MarkupDisplay::from(askama_expr)",
+ });
+ self.writeln("))?;");
+ }
+
+ fn write_lit(&mut self, lws: &'a str, val: &str, rws: &'a str) {
+ assert!(self.next_ws.is_none());
+ if !lws.is_empty() {
+ if self.skip_ws {
+ self.skip_ws = false;
+ } else if val.is_empty() {
+ assert!(rws.is_empty());
+ self.next_ws = Some(lws);
+ } else {
+ self.writeln(&format!("writer.write_str({:#?})?;", lws));
+ }
+ }
+ if !val.is_empty() {
+ self.writeln(&format!("writer.write_str({:#?})?;", val));
+ }
+ if !rws.is_empty() {
+ self.next_ws = Some(rws);
+ }
+ }
+
+ /* Visitor methods for expression types */
+
+ fn visit_expr(&mut self, expr: &Expr) -> DisplayWrap {
+ match *expr {
+ Expr::NumLit(s) => self.visit_num_lit(s),
+ Expr::StrLit(s) => self.visit_str_lit(s),
+ Expr::Var(s) => self.visit_var(s),
+ Expr::Path(ref path) => self.visit_path(path),
+ Expr::Array(ref elements) => self.visit_array(elements),
+ Expr::Attr(ref obj, name) => self.visit_attr(obj, name),
+ Expr::Filter(name, ref args) => self.visit_filter(name, args),
+ Expr::BinOp(op, ref left, ref right) => self.visit_binop(op, left, right),
+ Expr::Group(ref inner) => self.visit_group(inner),
+ Expr::MethodCall(ref obj, method, ref args) => {
+ self.visit_method_call(obj, method, args)
+ },
+ }
+ }
+
+ fn visit_match_variant(&mut self, param: &MatchVariant) -> DisplayWrap {
+ match *param {
+ MatchVariant::StrLit(s) => self.visit_str_lit(s),
+ MatchVariant::NumLit(s) => {
+ // Variants need to be references until match-modes land
+ self.write("&");
+ self.visit_num_lit(s)
+ },
+ MatchVariant::Name(s) => {
+ self.write("&");
+ self.write(s);
+ DisplayWrap::Unwrapped
+ },
+ MatchVariant::Path(ref s) => {
+ self.write("&");
+ self.write(&s.join("::"));
+ DisplayWrap::Unwrapped
+ },
+ }
+ }
+
+ fn visit_match_param(&mut self, param: &MatchParameter) -> DisplayWrap {
+ match *param {
+ MatchParameter::NumLit(s) => self.visit_num_lit(s),
+ MatchParameter::StrLit(s) => self.visit_str_lit(s),
+ MatchParameter::Name(s) => {
+ self.write("ref ");
+ self.write(s);
+ DisplayWrap::Unwrapped
+ },
+ }
+ }
+
+ fn visit_filter(&mut self, name: &str, args: &[Expr]) -> DisplayWrap {
+ if name == "format" {
+ self._visit_format_filter(args);
+ return DisplayWrap::Unwrapped;
+ } else if name == "join" {
+ self._visit_join_filter(args);
+ return DisplayWrap::Unwrapped;
+ }
+
+ if filters::BUILT_IN_FILTERS.contains(&name) {
+ self.write(&format!("::askama::filters::{}(&", name));
+ } else {
+ self.write(&format!("filters::{}(&", name));
+ }
+
+ self._visit_filter_args(args);
+ self.write(")?");
+ if name == "safe" || name == "escape" || name == "e" || name == "json" {
+ DisplayWrap::Wrapped
+ } else {
+ DisplayWrap::Unwrapped
+ }
+ }
+
+ fn _visit_format_filter(&mut self, args: &[Expr]) {
+ self.write("format!(");
+ self._visit_filter_args(args);
+ self.write(")");
+ }
+
+ // Force type coercion on first argument to `join` filter (see #39).
+ fn _visit_join_filter(&mut self, args: &[Expr]) {
+ self.write("::askama::filters::join((&");
+ for (i, arg) in args.iter().enumerate() {
+ if i > 0 {
+ self.write(", &");
+ }
+ self.visit_expr(arg);
+ if i == 0 {
+ self.write(").into_iter()");
+ }
+ }
+ self.write(")?");
+ }
+
+ fn _visit_filter_args(&mut self, args: &[Expr]) {
+ for (i, arg) in args.iter().enumerate() {
+ if i > 0 {
+ self.write(", &");
+ }
+ self.visit_expr(arg);
+ }
+ }
+
+ fn visit_attr(&mut self, obj: &Expr, attr: &str) -> DisplayWrap {
+ if let Expr::Var(name) = *obj {
+ if name == "loop" {
+ self.write("_loop_index");
+ if attr == "index" {
+ self.write(" + 1");
+ return DisplayWrap::Unwrapped;
+ } else if attr == "index0" {
+ return DisplayWrap::Unwrapped;
+ } else {
+ panic!("unknown loop variable");
+ }
+ }
+ }
+ self.visit_expr(obj);
+ self.write(&format!(".{}", attr));
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_method_call(&mut self, obj: &Expr, method: &str, args: &[Expr]) -> DisplayWrap {
+ self.visit_expr(obj);
+ self.write(&format!(".{}(", method));
+ for (i, arg) in args.iter().enumerate() {
+ if i > 0 {
+ self.write(", ");
+ }
+ self.visit_expr(arg);
+ }
+ self.write(")");
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_binop(&mut self, op: &str, left: &Expr, right: &Expr) -> DisplayWrap {
+ self.visit_expr(left);
+ self.write(&format!(" {} ", op));
+ self.visit_expr(right);
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_group(&mut self, inner: &Expr) -> DisplayWrap {
+ self.write("(");
+ self.visit_expr(inner);
+ self.write(")");
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_array(&mut self, elements: &[Expr]) -> DisplayWrap {
+ self.write("[");
+ for (i, el) in elements.iter().enumerate() {
+ if i > 0 {
+ self.write(", ");
+ }
+ self.visit_expr(el);
+ }
+ self.write("]");
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_path(&mut self, path: &[&str]) -> DisplayWrap {
+ for (i, part) in path.iter().enumerate() {
+ if i > 0 {
+ self.write("::");
+ }
+ self.write(part);
+ }
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_var(&mut self, s: &str) -> DisplayWrap {
+ if self.locals.contains(s) {
+ self.write(s);
+ } else {
+ self.write(&format!("self.{}", s));
+ }
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_str_lit(&mut self, s: &str) -> DisplayWrap {
+ self.write(&format!("\"{}\"", s));
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_num_lit(&mut self, s: &str) -> DisplayWrap {
+ self.write(s);
+ DisplayWrap::Unwrapped
+ }
+
+ fn visit_target_single<'t>(&mut self, name: &'t str) -> Vec<&'t str> {
+ vec![name]
+ }
+
+ fn visit_target<'t>(&mut self, target: &'t Target) -> Vec<&'t str> {
+ match *target {
+ Target::Name(s) => self.visit_target_single(s),
+ }
+ }
+
+ /* Helper methods for dealing with whitespace nodes */
+
+ // Combines `flush_ws()` and `prepare_ws()` to handle both trailing whitespace from the
+ // preceding literal and leading whitespace from the succeeding literal.
+ fn handle_ws(&mut self, ws: &WS) {
+ self.flush_ws(ws);
+ self.prepare_ws(ws);
+ }
+
+ // If the previous literal left some trailing whitespace in `next_ws` and the
+ // prefix whitespace suppressor from the given argument, flush that whitespace.
+ // In either case, `next_ws` is reset to `None` (no trailing whitespace).
+ fn flush_ws(&mut self, ws: &WS) {
+ if self.next_ws.is_some() && !ws.0 {
+ let val = self.next_ws.unwrap();
+ if !val.is_empty() {
+ self.writeln(&format!("writer.write_str({:#?})?;", val));
+ }
+ }
+ self.next_ws = None;
+ }
+
+ // Sets `skip_ws` to match the suffix whitespace suppressor from the given
+ // argument, to determine whether to suppress leading whitespace from the
+ // next literal.
+ fn prepare_ws(&mut self, ws: &WS) {
+ self.skip_ws = ws.1;
+ }
+
+ /* Helper methods for writing to internal buffer */
+
+ fn writeln(&mut self, s: &str) {
+ if s.is_empty() {
+ return;
+ }
+ if s == "}" {
+ self.dedent();
+ }
+ self.write(s);
+ if s.ends_with('{') {
+ self.indent();
+ }
+ self.buf.push('\n');
+ self.start = true;
+ }
+
+ fn write(&mut self, s: &str) {
+ if self.start {
+ for _ in 0..(self.indent * 4) {
+ self.buf.push(' ');
+ }
+ self.start = false;
+ }
+ self.buf.push_str(s);
+ }
+
+ fn indent(&mut self) {
+ self.indent += 1;
+ }
+
+ fn dedent(&mut self) {
+ if self.indent == 0 {
+ panic!("dedent() called while indentation == 0");
+ }
+ self.indent -= 1;
+ }
+}
+
+struct SetChain<'a, T: 'a> where T: cmp::Eq + hash::Hash {
+ parent: Option<&'a SetChain<'a, T>>,
+ scopes: Vec<HashSet<T>>,
+}
+
+impl<'a, T: 'a> SetChain<'a, T> where T: cmp::Eq + hash::Hash {
+ fn new() -> SetChain<'a, T> {
+ SetChain { parent: None, scopes: vec![HashSet::new()] }
+ }
+ fn with_parent<'p>(parent: &'p SetChain<T>) -> SetChain<'p, T> {
+ SetChain { parent: Some(parent), scopes: vec![HashSet::new()] }
+ }
+ fn contains(&self, val: T) -> bool {
+ self.scopes.iter().rev().any(|set| set.contains(&val)) || match self.parent {
+ Some(set) => set.contains(val),
+ None => false,
+ }
+ }
+ fn insert(&mut self, val: T) {
+ self.scopes.last_mut().unwrap().insert(val);
+ }
+ fn push(&mut self) {
+ self.scopes.push(HashSet::new());
+ }
+ fn pop(&mut self) {
+ self.scopes.pop().unwrap();
+ assert!(!self.scopes.is_empty());
+ }
+}
+
+#[derive(Clone)]
+enum AstLevel {
+ Top,
+ Nested,
+}
+
+impl Copy for AstLevel {}
+
+#[derive(Clone)]
+enum DisplayWrap {
+ Wrapped,
+ Unwrapped,
+}
+
+impl Copy for DisplayWrap {}
+
+type MacroMap<'a> = HashMap<(Option<&'a str>, &'a str), &'a Macro<'a>>;