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askama/askama_shared/src/generator.rs
René Kijewski c3e8b2cc72 Move visit_match_params into its own method
2021-07-01 10:24:32 +02:00

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use super::{get_template_source, CompileError, Integrations};
use crate::filters;
use crate::heritage::{Context, Heritage};
use crate::input::{Source, TemplateInput};
use crate::parser::{
parse, Cond, Expr, MatchParameter, MatchParameters, MatchVariant, Node, Target, When, Ws,
};
use proc_macro2::Span;
use quote::{quote, ToTokens};
use std::collections::HashMap;
use std::path::PathBuf;
use std::{cmp, hash, mem, str};
pub fn generate<S: std::hash::BuildHasher>(
input: &TemplateInput,
contexts: &HashMap<&PathBuf, Context, S>,
heritage: &Option<Heritage>,
integrations: Integrations,
) -> Result<String, CompileError> {
Generator::new(input, contexts, heritage, integrations, MapChain::new())
.build(&contexts[&input.path])
}
struct Generator<'a, S: std::hash::BuildHasher> {
// The template input state: original struct AST and attributes
input: &'a TemplateInput<'a>,
// All contexts, keyed by the package-relative template path
contexts: &'a HashMap<&'a PathBuf, Context<'a>, S>,
// The heritage contains references to blocks and their ancestry
heritage: &'a Option<Heritage<'a>>,
// What integrations need to be generated
integrations: Integrations,
// Variables accessible directly from the current scope (not redirected to context)
locals: MapChain<'a, &'a str, LocalMeta>,
// Suffix whitespace from the previous literal. Will be flushed to the
// output buffer unless suppressed by whitespace suppression on the next
// non-literal.
next_ws: Option<&'a str>,
// Whitespace suppression from the previous non-literal. Will be used to
// determine whether to flush prefix whitespace from the next literal.
skip_ws: bool,
// If currently in a block, this will contain the name of a potential parent block
super_block: Option<(&'a str, usize)>,
// buffer for writable
buf_writable: Vec<Writable<'a>>,
// Counter for write! hash named arguments
named: usize,
}
impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
fn new<'n>(
input: &'n TemplateInput,
contexts: &'n HashMap<&'n PathBuf, Context<'n>, S>,
heritage: &'n Option<Heritage>,
integrations: Integrations,
locals: MapChain<'n, &'n str, LocalMeta>,
) -> Generator<'n, S> {
Generator {
input,
contexts,
heritage,
integrations,
locals,
next_ws: None,
skip_ws: false,
super_block: None,
buf_writable: vec![],
named: 0,
}
}
fn child(&mut self) -> Generator<'_, S> {
let locals = MapChain::with_parent(&self.locals);
Self::new(
self.input,
self.contexts,
self.heritage,
self.integrations,
locals,
)
}
// Takes a Context and generates the relevant implementations.
fn build(mut self, ctx: &'a Context) -> Result<String, CompileError> {
let mut buf = Buffer::new(0);
if !ctx.blocks.is_empty() {
if let Some(parent) = self.input.parent {
self.deref_to_parent(&mut buf, parent)?;
}
};
self.impl_template(ctx, &mut buf)?;
self.impl_display(&mut buf)?;
if self.integrations.actix {
self.impl_actix_web_responder(&mut buf)?;
}
if self.integrations.gotham {
self.impl_gotham_into_response(&mut buf)?;
}
if self.integrations.iron {
self.impl_iron_modifier_response(&mut buf)?;
}
if self.integrations.mendes {
self.impl_mendes_responder(&mut buf)?;
}
if self.integrations.rocket {
self.impl_rocket_responder(&mut buf)?;
}
if self.integrations.tide {
self.impl_tide_integrations(&mut buf)?;
}
if self.integrations.warp {
self.impl_warp_reply(&mut buf)?;
}
Ok(buf.buf)
}
// Implement `Template` for the given context struct.
fn impl_template(&mut self, ctx: &'a Context, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(buf, "::askama::Template", None)?;
buf.writeln(
"fn render_into(&self, writer: &mut dyn ::std::fmt::Write) -> \
::askama::Result<()> {",
)?;
// Make sure the compiler understands that the generated code depends on the template files.
for path in self.contexts.keys() {
// Skip the fake path of templates defined in rust source.
let path_is_valid = match self.input.source {
Source::Path(_) => true,
Source::Source(_) => *path != &self.input.path,
};
if path_is_valid {
let path = path.to_str().unwrap();
buf.writeln(
&quote! {
include_bytes!(#path);
}
.to_string(),
)?;
}
}
let size_hint = if let Some(heritage) = self.heritage {
self.handle(heritage.root, heritage.root.nodes, buf, AstLevel::Top)
} else {
self.handle(ctx, ctx.nodes, buf, AstLevel::Top)
}?;
self.flush_ws(Ws(false, false));
buf.writeln("Ok(())")?;
buf.writeln("}")?;
buf.writeln("fn extension(&self) -> Option<&'static str> {")?;
buf.writeln(&format!("{:?}", self.input.extension()))?;
buf.writeln("}")?;
buf.writeln("fn size_hint(&self) -> usize {")?;
buf.writeln(&format!("{}", size_hint))?;
buf.writeln("}")?;
buf.writeln("}")?;
self.write_header(buf, "::askama::SizedTemplate", None)?;
buf.writeln("fn size_hint() -> usize {")?;
buf.writeln(&format!("{}", size_hint))?;
buf.writeln("}")?;
buf.writeln("fn extension() -> Option<&'static str> {")?;
buf.writeln(&format!("{:?}", self.input.extension()))?;
buf.writeln("}")?;
buf.writeln("}")?;
Ok(())
}
// Implement `Deref<Parent>` for an inheriting context struct.
fn deref_to_parent(
&mut self,
buf: &mut Buffer,
parent_type: &syn::Type,
) -> Result<(), CompileError> {
self.write_header(buf, "::std::ops::Deref", None)?;
buf.writeln(&format!(
"type Target = {};",
parent_type.into_token_stream()
))?;
buf.writeln("fn deref(&self) -> &Self::Target {")?;
buf.writeln("&self._parent")?;
buf.writeln("}")?;
buf.writeln("}")
}
// Implement `Display` for the given context struct.
fn impl_display(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(buf, "::std::fmt::Display", None)?;
buf.writeln("fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {")?;
buf.writeln("::askama::Template::render_into(self, f).map_err(|_| ::std::fmt::Error {})")?;
buf.writeln("}")?;
buf.writeln("}")
}
// Implement Actix-web's `Responder`.
fn impl_actix_web_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(buf, "::actix_web::Responder", None)?;
buf.writeln("type Future = ::askama_actix::futures::Ready<::std::result::Result<::actix_web::HttpResponse, Self::Error>>;")?;
buf.writeln("type Error = ::actix_web::Error;")?;
buf.writeln(
"fn respond_to(self, _req: &::actix_web::HttpRequest) \
-> Self::Future {",
)?;
buf.writeln("use ::askama_actix::TemplateToResponse;")?;
buf.writeln("::askama_actix::futures::ready(self.to_response())")?;
buf.writeln("}")?;
buf.writeln("}")
}
// Implement gotham's `IntoResponse`.
fn impl_gotham_into_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(buf, "::askama_gotham::IntoResponse", None)?;
buf.writeln(
"fn into_response(self, _state: &::askama_gotham::State)\
-> ::askama_gotham::Response<::askama_gotham::Body> {",
)?;
let ext = self.input.extension().unwrap_or("txt");
buf.writeln(&format!("::askama_gotham::respond(&self, {:?})", ext))?;
buf.writeln("}")?;
buf.writeln("}")
}
// Implement iron's Modifier<Response> if enabled
fn impl_iron_modifier_response(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(
buf,
"::askama_iron::Modifier<::askama_iron::Response>",
None,
)?;
buf.writeln("fn modify(self, res: &mut ::askama_iron::Response) {")?;
buf.writeln(
"res.body = Some(Box::new(::askama_iron::Template::render(&self).unwrap().into_bytes()));",
)?;
match self.input.extension().unwrap_or("") {
"html" | "htm" => {
buf.writeln("::askama_iron::ContentType::html().0.modify(res);")?;
}
_ => (),
};
buf.writeln("}")?;
buf.writeln("}")
}
// Implement mendes' `Responder`.
fn impl_mendes_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
let param = syn::parse_str("A: ::mendes::Application").unwrap();
let mut generics = self.input.ast.generics.clone();
generics.params.push(param);
let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
let (impl_generics, _, where_clause) = generics.split_for_impl();
let mut where_clause = match where_clause {
Some(clause) => clause.clone(),
None => syn::WhereClause {
where_token: syn::Token![where](Span::call_site()),
predicates: syn::punctuated::Punctuated::new(),
},
};
where_clause
.predicates
.push(syn::parse_str("A::ResponseBody: From<String>").unwrap());
where_clause
.predicates
.push(syn::parse_str("A::Error: From<::mendes::askama::Error>").unwrap());
buf.writeln(
format!(
"{} {} for {} {} {{",
quote!(impl#impl_generics),
"::mendes::application::Responder<A>",
self.input.ast.ident,
quote!(#orig_ty_generics #where_clause),
)
.as_ref(),
)?;
buf.writeln(
"fn into_response(self, app: &A, req: &::mendes::http::request::Parts) \
-> ::mendes::http::Response<A::ResponseBody> {",
)?;
buf.writeln(&format!(
"::mendes::askama::into_response(app, req, &self, {:?})",
self.input.extension()
))?;
buf.writeln("}")?;
buf.writeln("}")?;
Ok(())
}
// Implement Rocket's `Responder`.
fn impl_rocket_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
let lifetime = syn::Lifetime::new("'askama", Span::call_site());
let param = syn::GenericParam::Lifetime(syn::LifetimeDef::new(lifetime));
self.write_header(
buf,
"::askama_rocket::Responder<'askama, 'static>",
Some(vec![param]),
)?;
buf.writeln(
"fn respond_to(self, _: &::askama_rocket::Request) \
-> ::askama_rocket::Result<'static> {",
)?;
let ext = self.input.extension().unwrap_or("txt");
buf.writeln(&format!("::askama_rocket::respond(&self, {:?})", ext))?;
buf.writeln("}")?;
buf.writeln("}")?;
Ok(())
}
fn impl_tide_integrations(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
let ext = self.input.extension().unwrap_or("txt");
self.write_header(
buf,
"std::convert::TryInto<::askama_tide::tide::Body>",
None,
)?;
buf.writeln(
"type Error = ::askama_tide::askama::Error;\n\
fn try_into(self) -> ::askama_tide::askama::Result<::askama_tide::tide::Body> {",
)?;
buf.writeln(&format!("::askama_tide::try_into_body(&self, {:?})", &ext))?;
buf.writeln("}")?;
buf.writeln("}")?;
buf.writeln("#[allow(clippy::from_over_into)]")?;
self.write_header(buf, "Into<::askama_tide::tide::Response>", None)?;
buf.writeln("fn into(self) -> ::askama_tide::tide::Response {")?;
buf.writeln(&format!("::askama_tide::into_response(&self, {:?})", ext))?;
buf.writeln("}\n}")
}
fn impl_warp_reply(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
self.write_header(buf, "::askama_warp::warp::reply::Reply", None)?;
buf.writeln("fn into_response(self) -> ::askama_warp::warp::reply::Response {")?;
let ext = self.input.extension().unwrap_or("txt");
buf.writeln(&format!("::askama_warp::reply(&self, {:?})", ext))?;
buf.writeln("}")?;
buf.writeln("}")
}
// Writes header for the `impl` for `TraitFromPathName` or `Template`
// for the given context struct.
fn write_header(
&mut self,
buf: &mut Buffer,
target: &str,
params: Option<Vec<syn::GenericParam>>,
) -> Result<(), CompileError> {
let mut generics = self.input.ast.generics.clone();
if let Some(params) = params {
for param in params {
generics.params.push(param);
}
}
let (_, orig_ty_generics, _) = self.input.ast.generics.split_for_impl();
let (impl_generics, _, where_clause) = generics.split_for_impl();
buf.writeln(
format!(
"{} {} for {}{} {{",
quote!(impl#impl_generics),
target,
self.input.ast.ident,
quote!(#orig_ty_generics #where_clause),
)
.as_ref(),
)
}
/* Helper methods for handling node types */
fn handle(
&mut self,
ctx: &'a Context,
nodes: &'a [Node],
buf: &mut Buffer,
level: AstLevel,
) -> Result<usize, CompileError> {
let mut size_hint = 0;
for n in nodes {
match *n {
Node::Lit(lws, val, rws) => {
self.visit_lit(lws, val, rws);
}
Node::Comment(ws) => {
self.write_comment(ws);
}
Node::Expr(ws, ref val) => {
self.write_expr(ws, val);
}
Node::LetDecl(ws, ref var) => {
self.write_let_decl(buf, ws, var)?;
}
Node::Let(ws, ref var, ref val) => {
self.write_let(buf, ws, var, val)?;
}
Node::Cond(ref conds, ws) => {
self.write_cond(ctx, buf, conds, ws)?;
}
Node::Match(ws1, ref expr, ref arms, ws2) => {
self.write_match(ctx, buf, ws1, expr, arms, ws2)?;
}
Node::Loop(ws1, ref var, ref iter, ref body, ws2) => {
self.write_loop(ctx, buf, ws1, var, iter, body, ws2)?;
}
Node::BlockDef(ws1, name, _, ws2) => {
self.write_block(buf, Some(name), Ws(ws1.0, ws2.1))?;
}
Node::Include(ws, path) => {
size_hint += self.handle_include(ctx, buf, ws, path)?;
}
Node::Call(ws, scope, name, ref args) => {
size_hint += self.write_call(ctx, buf, ws, scope, name, args)?;
}
Node::Macro(_, ref m) => {
if level != AstLevel::Top {
return Err("macro blocks only allowed at the top level".into());
}
self.flush_ws(m.ws1);
self.prepare_ws(m.ws2);
}
Node::Raw(ws1, contents, ws2) => {
self.handle_ws(ws1);
self.buf_writable.push(Writable::Lit(contents));
self.handle_ws(ws2);
}
Node::Import(ws, _, _) => {
if level != AstLevel::Top {
return Err("import blocks only allowed at the top level".into());
}
self.handle_ws(ws);
}
Node::Extends(_) => {
if level != AstLevel::Top {
return Err("extend blocks only allowed at the top level".into());
}
// No whitespace handling: child template top-level is not used,
// except for the blocks defined in it.
}
}
}
if AstLevel::Top == level {
size_hint += self.write_buf_writable(buf)?;
}
Ok(size_hint)
}
fn write_cond(
&mut self,
ctx: &'a Context,
buf: &mut Buffer,
conds: &'a [Cond],
ws: Ws,
) -> Result<usize, CompileError> {
let mut flushed = 0;
let mut arm_sizes = Vec::new();
let mut has_else = false;
for (i, &(cws, ref cond, ref nodes)) in conds.iter().enumerate() {
self.handle_ws(cws);
flushed += self.write_buf_writable(buf)?;
if i > 0 {
self.locals.pop();
}
let mut arm_size = 0;
match *cond {
Some(ref expr) => {
if i == 0 {
buf.write("if ");
} else {
buf.dedent()?;
buf.write("} else if ");
}
// The following syntax `*(&(...) as &bool)` is used to
// trigger Rust's automatic dereferencing, to coerce
// e.g. `&&&&&bool` to `bool`. First `&(...) as &bool`
// coerces e.g. `&&&bool` to `&bool`. Then `*(&bool)`
// finally dereferences it to `bool`.
buf.write("*(&(");
let expr_code = self.visit_expr_root(expr)?;
buf.write(&expr_code);
buf.write(") as &bool)");
}
None => {
buf.dedent()?;
buf.write("} else");
has_else = true;
}
}
buf.writeln(" {")?;
self.locals.push();
arm_size += self.handle(ctx, nodes, buf, AstLevel::Nested)?;
arm_sizes.push(arm_size);
}
self.handle_ws(ws);
flushed += self.write_buf_writable(buf)?;
buf.writeln("}")?;
self.locals.pop();
if !has_else {
arm_sizes.push(0);
}
Ok(flushed + median(&mut arm_sizes))
}
#[allow(clippy::too_many_arguments)]
fn write_match(
&mut self,
ctx: &'a Context,
buf: &mut Buffer,
ws1: Ws,
expr: &Expr,
arms: &'a [When],
ws2: Ws,
) -> Result<usize, CompileError> {
self.flush_ws(ws1);
let flushed = self.write_buf_writable(buf)?;
let mut arm_sizes = Vec::new();
let expr_code = self.visit_expr_root(expr)?;
buf.writeln(&format!("match &{} {{", expr_code))?;
let mut arm_size = 0;
for (i, arm) in arms.iter().enumerate() {
let &(ws, ref variant, ref params, ref body) = arm;
self.handle_ws(ws);
if i > 0 {
arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
buf.writeln("}")?;
self.locals.pop();
}
self.locals.push();
match *variant {
Some(ref param) => {
self.visit_match_variant(buf, param);
}
None => buf.write("_"),
};
self.visit_match_params(buf, params);
buf.writeln(" => {")?;
arm_size = self.handle(ctx, body, buf, AstLevel::Nested)?;
}
self.handle_ws(ws2);
arm_sizes.push(arm_size + self.write_buf_writable(buf)?);
buf.writeln("}")?;
self.locals.pop();
buf.writeln("}")?;
Ok(flushed + median(&mut arm_sizes))
}
#[allow(clippy::too_many_arguments)]
fn write_loop(
&mut self,
ctx: &'a Context,
buf: &mut Buffer,
ws1: Ws,
var: &'a Target,
iter: &Expr,
body: &'a [Node],
ws2: Ws,
) -> Result<usize, CompileError> {
self.handle_ws(ws1);
self.locals.push();
let expr_code = self.visit_expr_root(iter)?;
let flushed = self.write_buf_writable(buf)?;
buf.write("for (");
self.visit_target(buf, var);
match iter {
Expr::Range(_, _, _) => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new({}) {{",
expr_code
)),
Expr::Array(..) => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new({}.iter()) {{",
expr_code
)),
// If `iter` is a call then we assume it's something that returns
// an iterator. If not then the user can explicitly add the needed
// call without issues.
Expr::MethodCall(..) | Expr::PathCall(..) | Expr::Index(..) => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new(({}).into_iter()) {{",
expr_code
)),
// If accessing `self` then it most likely needs to be
// borrowed, to prevent an attempt of moving.
_ if expr_code.starts_with("self.") => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new(((&{}).into_iter())) {{",
expr_code
)),
// If accessing a field then it most likely needs to be
// borrowed, to prevent an attempt of moving.
Expr::Attr(..) => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new(((&{}).into_iter())) {{",
expr_code
)),
// Otherwise, we borrow `iter` assuming that it implements `IntoIterator`.
_ => buf.writeln(&format!(
", _loop_item) in ::askama::helpers::TemplateLoop::new(({}).into_iter()) {{",
expr_code
)),
}?;
let mut size_hint = self.handle(ctx, body, buf, AstLevel::Nested)?;
self.handle_ws(ws2);
size_hint += self.write_buf_writable(buf)?;
buf.writeln("}")?;
self.locals.pop();
Ok(flushed + (size_hint * 3))
}
fn write_call(
&mut self,
ctx: &'a Context,
buf: &mut Buffer,
ws: Ws,
scope: Option<&str>,
name: &str,
args: &[Expr],
) -> Result<usize, CompileError> {
if name == "super" {
return self.write_block(buf, None, ws);
}
let (def, own_ctx) = if let Some(s) = scope {
let path = ctx.imports.get(s).ok_or_else(|| {
CompileError::String(format!("no import found for scope '{}'", s))
})?;
let mctx = self.contexts.get(path).ok_or_else(|| {
CompileError::String(format!("context for '{:?}' not found", path))
})?;
(
mctx.macros.get(name).ok_or_else(|| {
CompileError::String(format!("macro '{}' not found in scope '{}'", name, s))
})?,
mctx,
)
} else {
(
ctx.macros
.get(name)
.ok_or_else(|| CompileError::String(format!("macro '{}' not found", name)))?,
ctx,
)
};
self.flush_ws(ws); // Cannot handle_ws() here: whitespace from macro definition comes first
self.locals.push();
self.write_buf_writable(buf)?;
buf.writeln("{")?;
self.prepare_ws(def.ws1);
let mut names = Buffer::new(0);
let mut values = Buffer::new(0);
let mut is_first_variable = true;
for (i, arg) in def.args.iter().enumerate() {
let expr = args.get(i).ok_or_else(|| {
CompileError::String(format!("macro '{}' takes more than {} arguments", name, i))
})?;
match expr {
// If `expr` is already a form of variable then
// don't reintroduce a new variable. This is
// to avoid moving non-copyable values.
Expr::Var(name) => {
let var = self.locals.resolve_or_self(name);
self.locals.insert(arg, LocalMeta::with_ref(var));
}
Expr::Attr(obj, attr) => {
let mut attr_buf = Buffer::new(0);
self.visit_attr(&mut attr_buf, obj, attr)?;
let var = self.locals.resolve(&attr_buf.buf).unwrap_or(attr_buf.buf);
self.locals.insert(arg, LocalMeta::with_ref(var));
}
// Everything else still needs to become variables,
// to avoid having the same logic be executed
// multiple times, e.g. in the case of macro
// parameters being used multiple times.
_ => {
if is_first_variable {
is_first_variable = false
} else {
names.write(", ");
values.write(", ");
}
names.write(arg);
values.write("(");
values.write(&self.visit_expr_root(expr)?);
values.write(")");
self.locals.insert_with_default(arg);
}
}
}
debug_assert_eq!(names.buf.is_empty(), values.buf.is_empty());
if !names.buf.is_empty() {
buf.writeln(&format!("let ({}) = ({});", names.buf, values.buf))?;
}
let mut size_hint = self.handle(own_ctx, &def.nodes, buf, AstLevel::Nested)?;
self.flush_ws(def.ws2);
size_hint += self.write_buf_writable(buf)?;
buf.writeln("}")?;
self.locals.pop();
self.prepare_ws(ws);
Ok(size_hint)
}
fn handle_include(
&mut self,
ctx: &'a Context,
buf: &mut Buffer,
ws: Ws,
path: &str,
) -> Result<usize, CompileError> {
self.flush_ws(ws);
self.write_buf_writable(buf)?;
let path = self
.input
.config
.find_template(path, Some(&self.input.path))?;
let src = get_template_source(&path)?;
let nodes = parse(&src, self.input.syntax)?;
// Make sure the compiler understands that the generated code depends on the template file.
{
let path = path.to_str().unwrap();
buf.writeln(
&quote! {
include_bytes!(#path);
}
.to_string(),
)?;
}
let size_hint = {
// Since nodes must not outlive the Generator, we instantiate
// a nested Generator here to handle the include's nodes.
let mut gen = self.child();
let mut size_hint = gen.handle(ctx, &nodes, buf, AstLevel::Nested)?;
size_hint += gen.write_buf_writable(buf)?;
size_hint
};
self.prepare_ws(ws);
Ok(size_hint)
}
fn write_let_decl(
&mut self,
buf: &mut Buffer,
ws: Ws,
var: &'a Target,
) -> Result<(), CompileError> {
self.handle_ws(ws);
self.write_buf_writable(buf)?;
buf.write("let ");
match *var {
Target::Name(name) => {
let name = normalize_identifier(name);
self.locals.insert_with_default(name);
buf.write(name);
}
Target::Tuple(ref targets) => {
buf.write("(");
for name in targets {
let name = normalize_identifier(name);
self.locals.insert_with_default(name);
buf.write(name);
buf.write(",");
}
buf.write(")");
}
}
buf.writeln(";")
}
fn write_let(
&mut self,
buf: &mut Buffer,
ws: Ws,
var: &'a Target,
val: &Expr,
) -> Result<(), CompileError> {
self.handle_ws(ws);
let mut expr_buf = Buffer::new(0);
self.visit_expr(&mut expr_buf, val)?;
match *var {
Target::Name(name) => {
let name = normalize_identifier(name);
let meta = self.locals.get(&name).cloned();
let shadowed = matches!(&meta, Some(meta) if meta.initialized);
if shadowed {
// Need to flush the buffer if the variable is being shadowed,
// to ensure the old variable is used.
self.write_buf_writable(buf)?;
}
if shadowed || meta.is_none() {
buf.write("let ");
}
buf.write(name);
self.locals.insert(name, LocalMeta::initialized());
}
Target::Tuple(ref targets) => {
let shadowed = targets.iter().any(|name| {
let name = normalize_identifier(name);
matches!(self.locals.get(&name), Some(meta) if meta.initialized)
});
if shadowed {
// Need to flush the buffer if the variable is being shadowed,
// to ensure the old variable is used.
self.write_buf_writable(buf)?;
}
buf.write("let (");
for name in targets {
let name = normalize_identifier(name);
self.locals.insert(name, LocalMeta::initialized());
buf.write(name);
buf.write(",");
}
buf.write(")");
}
}
buf.writeln(&format!(" = {};", &expr_buf.buf))
}
// If `name` is `Some`, this is a call to a block definition, and we have to find
// the first block for that name from the ancestry chain. If name is `None`, this
// is from a `super()` call, and we can get the name from `self.super_block`.
fn write_block(
&mut self,
buf: &mut Buffer,
name: Option<&'a str>,
outer: Ws,
) -> Result<usize, CompileError> {
// Flush preceding whitespace according to the outer WS spec
self.flush_ws(outer);
let prev_block = self.super_block;
let cur = match (name, prev_block) {
// The top-level context contains a block definition
(Some(cur_name), None) => (cur_name, 0),
// A block definition contains a block definition of the same name
(Some(cur_name), Some((prev_name, _))) if cur_name == prev_name => {
return Err(format!("cannot define recursive blocks ({})", cur_name).into());
}
// A block definition contains a definition of another block
(Some(cur_name), Some((_, _))) => (cur_name, 0),
// `super()` was called inside a block
(None, Some((prev_name, gen))) => (prev_name, gen + 1),
// `super()` is called from outside a block
(None, None) => return Err("cannot call 'super()' outside block".into()),
};
self.super_block = Some(cur);
// Get the block definition from the heritage chain
let heritage = self
.heritage
.as_ref()
.ok_or(CompileError::Static("no block ancestors available"))?;
let (ctx, def) = heritage.blocks[cur.0].get(cur.1).ok_or_else(|| {
CompileError::from(match name {
None => format!("no super() block found for block '{}'", cur.0),
Some(name) => format!("no block found for name '{}'", name),
})
})?;
// Get the nodes and whitespace suppression data from the block definition
let (ws1, nodes, ws2) = if let Node::BlockDef(ws1, _, nodes, ws2) = def {
(ws1, nodes, ws2)
} else {
unreachable!()
};
// Handle inner whitespace suppression spec and process block nodes
self.prepare_ws(*ws1);
self.locals.push();
let size_hint = self.handle(ctx, nodes, buf, AstLevel::Block)?;
if !self.locals.is_current_empty() {
// Need to flush the buffer before popping the variable stack
self.write_buf_writable(buf)?;
}
self.locals.pop();
self.flush_ws(*ws2);
// Restore original block context and set whitespace suppression for
// succeeding whitespace according to the outer WS spec
self.super_block = prev_block;
self.prepare_ws(outer);
Ok(size_hint)
}
fn write_expr(&mut self, ws: Ws, s: &'a Expr<'a>) {
self.handle_ws(ws);
self.buf_writable.push(Writable::Expr(s));
}
// Write expression buffer and empty
fn write_buf_writable(&mut self, buf: &mut Buffer) -> Result<usize, CompileError> {
if self.buf_writable.is_empty() {
return Ok(0);
}
if self
.buf_writable
.iter()
.all(|w| matches!(w, Writable::Lit(_)))
{
let mut buf_lit = Buffer::new(0);
for s in mem::take(&mut self.buf_writable) {
if let Writable::Lit(s) = s {
buf_lit.write(s);
};
}
buf.writeln(&format!("writer.write_str({:#?})?;", &buf_lit.buf))?;
return Ok(buf_lit.buf.len());
}
let mut size_hint = 0;
let mut buf_format = Buffer::new(0);
let mut buf_expr = Buffer::new(buf.indent + 1);
let mut expr_cache = HashMap::with_capacity(self.buf_writable.len());
for s in mem::take(&mut self.buf_writable) {
match s {
Writable::Lit(s) => {
buf_format.write(&s.replace("{", "{{").replace("}", "}}"));
size_hint += s.len();
}
Writable::Expr(s) => {
use self::DisplayWrap::*;
let mut expr_buf = Buffer::new(0);
let wrapped = self.visit_expr(&mut expr_buf, s)?;
let expression = match wrapped {
Wrapped => expr_buf.buf,
Unwrapped => format!(
"::askama::MarkupDisplay::new_unsafe(&({}), {})",
expr_buf.buf, self.input.escaper
),
};
use std::collections::hash_map::Entry;
let id = match expr_cache.entry(expression.clone()) {
Entry::Occupied(e) => *e.get(),
Entry::Vacant(e) => {
let id = self.named;
self.named += 1;
buf_expr.write(&format!("expr{} = ", id));
buf_expr.write("&");
buf_expr.write(&expression);
buf_expr.writeln(",")?;
e.insert(id);
id
}
};
buf_format.write(&format!("{{expr{}}}", id));
size_hint += 3;
}
}
}
buf.writeln("write!(")?;
buf.indent();
buf.writeln("writer,")?;
buf.writeln(&format!("{:#?},", &buf_format.buf))?;
buf.writeln(buf_expr.buf.trim())?;
buf.dedent()?;
buf.writeln(")?;")?;
Ok(size_hint)
}
fn visit_lit(&mut self, lws: &'a str, val: &'a 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.buf_writable.push(Writable::Lit(lws));
}
}
if !val.is_empty() {
self.buf_writable.push(Writable::Lit(val));
}
if !rws.is_empty() {
self.next_ws = Some(rws);
}
}
fn write_comment(&mut self, ws: Ws) {
self.handle_ws(ws);
}
/* Visitor methods for expression types */
fn visit_expr_root(&mut self, expr: &Expr) -> Result<String, CompileError> {
let mut buf = Buffer::new(0);
self.visit_expr(&mut buf, expr)?;
Ok(buf.buf)
}
fn visit_expr(&mut self, buf: &mut Buffer, expr: &Expr) -> Result<DisplayWrap, CompileError> {
Ok(match *expr {
Expr::BoolLit(s) => self.visit_bool_lit(buf, s),
Expr::NumLit(s) => self.visit_num_lit(buf, s),
Expr::StrLit(s) => self.visit_str_lit(buf, s),
Expr::CharLit(s) => self.visit_char_lit(buf, s),
Expr::Var(s) => self.visit_var(buf, s),
Expr::VarCall(var, ref args) => self.visit_var_call(buf, var, args)?,
Expr::Path(ref path) => self.visit_path(buf, path),
Expr::PathCall(ref path, ref args) => self.visit_path_call(buf, path, args)?,
Expr::Array(ref elements) => self.visit_array(buf, elements)?,
Expr::Attr(ref obj, name) => self.visit_attr(buf, obj, name)?,
Expr::Index(ref obj, ref key) => self.visit_index(buf, obj, key)?,
Expr::Filter(name, ref args) => self.visit_filter(buf, name, args)?,
Expr::Unary(op, ref inner) => self.visit_unary(buf, op, inner)?,
Expr::BinOp(op, ref left, ref right) => self.visit_binop(buf, op, left, right)?,
Expr::Range(op, ref left, ref right) => self.visit_range(buf, op, left, right)?,
Expr::Group(ref inner) => self.visit_group(buf, inner)?,
Expr::MethodCall(ref obj, method, ref args) => {
self.visit_method_call(buf, obj, method, args)?
}
Expr::RustMacro(name, args) => self.visit_rust_macro(buf, name, args),
})
}
fn visit_rust_macro(&mut self, buf: &mut Buffer, name: &str, args: &str) -> DisplayWrap {
buf.write(name);
buf.write("!(");
buf.write(args);
buf.write(")");
DisplayWrap::Unwrapped
}
fn visit_match_variant(&mut self, buf: &mut Buffer, param: &MatchVariant) -> DisplayWrap {
let mut expr_buf = Buffer::new(0);
let wrapped = match *param {
MatchVariant::StrLit(s) => {
expr_buf.write("&");
self.visit_str_lit(&mut expr_buf, s)
}
MatchVariant::CharLit(s) => self.visit_char_lit(&mut expr_buf, s),
MatchVariant::NumLit(s) => self.visit_num_lit(&mut expr_buf, s),
MatchVariant::Name(s) => {
expr_buf.write(s);
DisplayWrap::Unwrapped
}
MatchVariant::Path(ref s) => {
expr_buf.write(&s.join("::"));
DisplayWrap::Unwrapped
}
};
buf.write(&expr_buf.buf);
wrapped
}
fn visit_match_param(&mut self, buf: &mut Buffer, param: &MatchParameter) -> DisplayWrap {
let mut expr_buf = Buffer::new(0);
let wrapped = match *param {
MatchParameter::NumLit(s) => self.visit_num_lit(&mut expr_buf, s),
MatchParameter::StrLit(s) => self.visit_str_lit(&mut expr_buf, s),
MatchParameter::CharLit(s) => self.visit_char_lit(&mut expr_buf, s),
MatchParameter::Name(s) => {
expr_buf.write(s);
DisplayWrap::Unwrapped
}
};
buf.write(&expr_buf.buf);
wrapped
}
fn visit_match_params(&mut self, buf: &mut Buffer, params: &MatchParameters<'a>) {
match params {
MatchParameters::Simple(params) => {
if !params.is_empty() {
buf.write("(");
for (i, param) in params.iter().enumerate() {
if let MatchParameter::Name(p) = *param {
self.locals.insert_with_default(p);
}
if i > 0 {
buf.write(", ");
}
self.visit_match_param(buf, param);
}
buf.write(")");
}
}
MatchParameters::Named(params) => {
buf.write("{");
for (i, param) in params.iter().enumerate() {
if let Some(MatchParameter::Name(p)) = param.1 {
let p = normalize_identifier(p);
self.locals.insert_with_default(p);
} else {
self.locals.insert_with_default(param.0);
}
if i > 0 {
buf.write(", ");
}
buf.write(param.0);
if let Some(param) = &param.1 {
buf.write(":");
self.visit_match_param(buf, param);
}
}
buf.write("}");
}
}
}
fn visit_filter(
&mut self,
buf: &mut Buffer,
mut name: &str,
args: &[Expr],
) -> Result<DisplayWrap, CompileError> {
if name == "format" {
self._visit_format_filter(buf, args)?;
return Ok(DisplayWrap::Unwrapped);
} else if name == "fmt" {
self._visit_fmt_filter(buf, args)?;
return Ok(DisplayWrap::Unwrapped);
} else if name == "join" {
self._visit_join_filter(buf, args)?;
return Ok(DisplayWrap::Unwrapped);
}
if name == "tojson" {
name = "json";
}
#[cfg(not(feature = "json"))]
if name == "json" {
return Err("the `json` filter requires the `serde-json` feature to be enabled".into());
}
#[cfg(not(feature = "yaml"))]
if name == "yaml" {
return Err("the `yaml` filter requires the `serde-yaml` feature to be enabled".into());
}
const FILTERS: [&str; 5] = ["safe", "escape", "e", "json", "yaml"];
if FILTERS.contains(&name) {
buf.write(&format!(
"::askama::filters::{}({}, ",
name, self.input.escaper
));
} else if filters::BUILT_IN_FILTERS.contains(&name) {
buf.write(&format!("::askama::filters::{}(", name));
} else {
buf.write(&format!("filters::{}(", name));
}
self._visit_args(buf, args)?;
buf.write(")?");
Ok(match FILTERS.contains(&name) {
true => DisplayWrap::Wrapped,
false => DisplayWrap::Unwrapped,
})
}
fn _visit_format_filter(
&mut self,
buf: &mut Buffer,
args: &[Expr],
) -> Result<(), CompileError> {
buf.write("format!(");
if let Some(Expr::StrLit(v)) = args.first() {
self.visit_str_lit(buf, v);
if args.len() > 1 {
buf.write(", ");
}
} else {
return Err("invalid expression type for format filter".into());
}
self._visit_args(buf, &args[1..])?;
buf.write(")");
Ok(())
}
fn _visit_fmt_filter(&mut self, buf: &mut Buffer, args: &[Expr]) -> Result<(), CompileError> {
buf.write("format!(");
if let Some(Expr::StrLit(v)) = args.get(1) {
self.visit_str_lit(buf, v);
buf.write(", ");
} else {
return Err("invalid expression type for fmt filter".into());
}
self._visit_args(buf, &args[0..1])?;
if args.len() > 2 {
return Err("only two arguments allowed to fmt filter".into());
}
buf.write(")");
Ok(())
}
// Force type coercion on first argument to `join` filter (see #39).
fn _visit_join_filter(&mut self, buf: &mut Buffer, args: &[Expr]) -> Result<(), CompileError> {
buf.write("::askama::filters::join((&");
for (i, arg) in args.iter().enumerate() {
if i > 0 {
buf.write(", &");
}
self.visit_expr(buf, arg)?;
if i == 0 {
buf.write(").into_iter()");
}
}
buf.write(")?");
Ok(())
}
fn _visit_args(&mut self, buf: &mut Buffer, args: &[Expr]) -> Result<(), CompileError> {
if args.is_empty() {
return Ok(());
}
for (i, arg) in args.iter().enumerate() {
if i > 0 {
buf.write(", ");
}
let borrow = !arg.is_copyable();
if borrow {
buf.write("&(");
}
let scoped = matches!(
arg,
Expr::Filter(_, _)
| Expr::MethodCall(_, _, _)
| Expr::VarCall(_, _)
| Expr::PathCall(_, _)
);
if scoped {
buf.writeln("{")?;
self.visit_expr(buf, arg)?;
buf.writeln("}")?;
} else {
self.visit_expr(buf, arg)?;
}
if borrow {
buf.write(")");
}
}
Ok(())
}
fn visit_attr(
&mut self,
buf: &mut Buffer,
obj: &Expr,
attr: &str,
) -> Result<DisplayWrap, CompileError> {
if let Expr::Var(name) = *obj {
if name == "loop" {
if attr == "index" {
buf.write("(_loop_item.index + 1)");
return Ok(DisplayWrap::Unwrapped);
} else if attr == "index0" {
buf.write("_loop_item.index");
return Ok(DisplayWrap::Unwrapped);
} else if attr == "first" {
buf.write("_loop_item.first");
return Ok(DisplayWrap::Unwrapped);
} else if attr == "last" {
buf.write("_loop_item.last");
return Ok(DisplayWrap::Unwrapped);
} else {
return Err("unknown loop variable".into());
}
}
}
self.visit_expr(buf, obj)?;
buf.write(&format!(".{}", attr));
Ok(DisplayWrap::Unwrapped)
}
fn visit_index(
&mut self,
buf: &mut Buffer,
obj: &Expr,
key: &Expr,
) -> Result<DisplayWrap, CompileError> {
buf.write("&");
self.visit_expr(buf, obj)?;
buf.write("[");
self.visit_expr(buf, key)?;
buf.write("]");
Ok(DisplayWrap::Unwrapped)
}
fn visit_method_call(
&mut self,
buf: &mut Buffer,
obj: &Expr,
method: &str,
args: &[Expr],
) -> Result<DisplayWrap, CompileError> {
if let Expr::Var("self") = obj {
buf.write("self");
} else {
self.visit_expr(buf, obj)?;
}
buf.write(&format!(".{}(", method));
self._visit_args(buf, args)?;
buf.write(")");
Ok(DisplayWrap::Unwrapped)
}
fn visit_unary(
&mut self,
buf: &mut Buffer,
op: &str,
inner: &Expr,
) -> Result<DisplayWrap, CompileError> {
buf.write(op);
self.visit_expr(buf, inner)?;
Ok(DisplayWrap::Unwrapped)
}
fn visit_range(
&mut self,
buf: &mut Buffer,
op: &str,
left: &Option<Box<Expr>>,
right: &Option<Box<Expr>>,
) -> Result<DisplayWrap, CompileError> {
if let Some(left) = left {
self.visit_expr(buf, left)?;
}
buf.write(op);
if let Some(right) = right {
self.visit_expr(buf, right)?;
}
Ok(DisplayWrap::Unwrapped)
}
fn visit_binop(
&mut self,
buf: &mut Buffer,
op: &str,
left: &Expr,
right: &Expr,
) -> Result<DisplayWrap, CompileError> {
self.visit_expr(buf, left)?;
buf.write(&format!(" {} ", op));
self.visit_expr(buf, right)?;
Ok(DisplayWrap::Unwrapped)
}
fn visit_group(&mut self, buf: &mut Buffer, inner: &Expr) -> Result<DisplayWrap, CompileError> {
buf.write("(");
self.visit_expr(buf, inner)?;
buf.write(")");
Ok(DisplayWrap::Unwrapped)
}
fn visit_array(
&mut self,
buf: &mut Buffer,
elements: &[Expr],
) -> Result<DisplayWrap, CompileError> {
buf.write("[");
for (i, el) in elements.iter().enumerate() {
if i > 0 {
buf.write(", ");
}
self.visit_expr(buf, el)?;
}
buf.write("]");
Ok(DisplayWrap::Unwrapped)
}
fn visit_path(&mut self, buf: &mut Buffer, path: &[&str]) -> DisplayWrap {
for (i, part) in path.iter().enumerate() {
if i > 0 {
buf.write("::");
}
buf.write(part);
}
DisplayWrap::Unwrapped
}
fn visit_path_call(
&mut self,
buf: &mut Buffer,
path: &[&str],
args: &[Expr],
) -> Result<DisplayWrap, CompileError> {
for (i, part) in path.iter().enumerate() {
if i > 0 {
buf.write("::");
}
buf.write(part);
}
buf.write("(");
self._visit_args(buf, args)?;
buf.write(")");
Ok(DisplayWrap::Unwrapped)
}
fn visit_var(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
if s == "self" {
buf.write(s);
return DisplayWrap::Unwrapped;
}
buf.write(normalize_identifier(&self.locals.resolve_or_self(s)));
DisplayWrap::Unwrapped
}
fn visit_var_call(
&mut self,
buf: &mut Buffer,
s: &str,
args: &[Expr],
) -> Result<DisplayWrap, CompileError> {
buf.write("(");
let s = normalize_identifier(s);
if !self.locals.contains(&s) && s != "self" {
buf.write("self.");
}
buf.write(s);
buf.write(")(");
self._visit_args(buf, args)?;
buf.write(")");
Ok(DisplayWrap::Unwrapped)
}
fn visit_bool_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
buf.write(s);
DisplayWrap::Unwrapped
}
fn visit_str_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
buf.write(&format!("\"{}\"", s));
DisplayWrap::Unwrapped
}
fn visit_char_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
buf.write(&format!("'{}'", s));
DisplayWrap::Unwrapped
}
fn visit_num_lit(&mut self, buf: &mut Buffer, s: &str) -> DisplayWrap {
buf.write(s);
DisplayWrap::Unwrapped
}
fn visit_target(&mut self, buf: &mut Buffer, target: &'a Target) {
match *target {
Target::Name(name) => {
let name = normalize_identifier(name);
self.locals.insert_with_default(name);
buf.write(name);
}
Target::Tuple(ref targets) => {
buf.write("(");
for name in targets {
let name = normalize_identifier(name);
self.locals.insert_with_default(name);
buf.write(name);
buf.write(",");
}
buf.write(")");
}
}
}
/* 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.buf_writable.push(Writable::Lit(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;
}
}
struct Buffer {
// The buffer to generate the code into
buf: String,
// The current level of indentation (in spaces)
indent: u8,
// Whether the output buffer is currently at the start of a line
start: bool,
}
impl Buffer {
fn new(indent: u8) -> Self {
Self {
buf: String::new(),
indent,
start: true,
}
}
fn writeln(&mut self, s: &str) -> Result<(), CompileError> {
if s == "}" {
self.dedent()?;
}
if !s.is_empty() {
self.write(s);
}
self.buf.push('\n');
if s.ends_with('{') {
self.indent();
}
self.start = true;
Ok(())
}
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) -> Result<(), CompileError> {
if self.indent == 0 {
return Err("dedent() called while indentation == 0".into());
}
self.indent -= 1;
Ok(())
}
}
#[derive(Clone, Default)]
struct LocalMeta {
refs: Option<String>,
initialized: bool,
}
impl LocalMeta {
fn initialized() -> Self {
Self {
refs: None,
initialized: true,
}
}
fn with_ref(refs: String) -> Self {
Self {
refs: Some(refs),
initialized: true,
}
}
}
// type SetChain<'a, T> = MapChain<'a, T, ()>;
#[derive(Debug)]
struct MapChain<'a, K: 'a, V: 'a>
where
K: cmp::Eq + hash::Hash,
{
parent: Option<&'a MapChain<'a, K, V>>,
scopes: Vec<HashMap<K, V>>,
}
impl<'a, K: 'a, V: 'a> MapChain<'a, K, V>
where
K: cmp::Eq + hash::Hash,
{
fn new() -> MapChain<'a, K, V> {
MapChain {
parent: None,
scopes: vec![HashMap::new()],
}
}
fn with_parent<'p>(parent: &'p MapChain<K, V>) -> MapChain<'p, K, V> {
MapChain {
parent: Some(parent),
scopes: vec![HashMap::new()],
}
}
fn contains(&self, key: &K) -> bool {
self.scopes.iter().rev().any(|set| set.contains_key(key))
|| match self.parent {
Some(set) => set.contains(key),
None => false,
}
}
/// Iterates the scopes in reverse and returns `Some(LocalMeta)`
/// from the first scope where `key` exists.
fn get(&self, key: &K) -> Option<&V> {
let scopes = self.scopes.iter().rev();
scopes
.filter_map(|set| set.get(key))
.next()
.or_else(|| self.parent.and_then(|set| set.get(key)))
}
fn is_current_empty(&self) -> bool {
self.scopes.last().unwrap().is_empty()
}
fn insert(&mut self, key: K, val: V) {
self.scopes.last_mut().unwrap().insert(key, val);
// Note that if `insert` returns `Some` then it implies
// an identifier is reused. For e.g. `{% macro f(a, a) %}`
// and `{% let (a, a) = ... %}` then this results in a
// generated template, which when compiled fails with the
// compile error "identifier `a` used more than once".
}
fn insert_with_default(&mut self, key: K)
where
V: Default,
{
self.insert(key, V::default());
}
fn push(&mut self) {
self.scopes.push(HashMap::new());
}
fn pop(&mut self) {
self.scopes.pop().unwrap();
assert!(!self.scopes.is_empty());
}
}
impl MapChain<'_, &str, LocalMeta> {
fn resolve(&self, name: &str) -> Option<String> {
let name = normalize_identifier(name);
self.get(&name).map(|meta| match &meta.refs {
Some(expr) => expr.clone(),
None => name.to_string(),
})
}
fn resolve_or_self(&self, name: &str) -> String {
let name = normalize_identifier(name);
self.resolve(name)
.unwrap_or_else(|| format!("self.{}", name))
}
}
fn median(sizes: &mut [usize]) -> usize {
sizes.sort_unstable();
if sizes.len() % 2 == 1 {
sizes[sizes.len() / 2]
} else {
(sizes[sizes.len() / 2 - 1] + sizes[sizes.len() / 2]) / 2
}
}
#[derive(Clone, PartialEq)]
enum AstLevel {
Top,
Block,
Nested,
}
impl Copy for AstLevel {}
#[derive(Clone)]
enum DisplayWrap {
Wrapped,
Unwrapped,
}
impl Copy for DisplayWrap {}
#[derive(Debug)]
enum Writable<'a> {
Lit(&'a str),
Expr(&'a Expr<'a>),
}
// Identifiers to be replaced with raw identifiers, so as to avoid
// collisions between template syntax and Rust's syntax. In particular
// [Rust keywords](https://doc.rust-lang.org/reference/keywords.html)
// should be replaced, since they're not reserved words in Askama
// syntax but have a high probability of causing problems in the
// generated code.
//
// This list excludes the Rust keywords *self*, *Self*, and *super*
// because they are not allowed to be raw identifiers, and *loop*
// because it's used something like a keyword in the template
// language.
static USE_RAW: [(&str, &str); 47] = [
("as", "r#as"),
("break", "r#break"),
("const", "r#const"),
("continue", "r#continue"),
("crate", "r#crate"),
("else", "r#else"),
("enum", "r#enum"),
("extern", "r#extern"),
("false", "r#false"),
("fn", "r#fn"),
("for", "r#for"),
("if", "r#if"),
("impl", "r#impl"),
("in", "r#in"),
("let", "r#let"),
("match", "r#match"),
("mod", "r#mod"),
("move", "r#move"),
("mut", "r#mut"),
("pub", "r#pub"),
("ref", "r#ref"),
("return", "r#return"),
("static", "r#static"),
("struct", "r#struct"),
("trait", "r#trait"),
("true", "r#true"),
("type", "r#type"),
("unsafe", "r#unsafe"),
("use", "r#use"),
("where", "r#where"),
("while", "r#while"),
("async", "r#async"),
("await", "r#await"),
("dyn", "r#dyn"),
("abstract", "r#abstract"),
("become", "r#become"),
("box", "r#box"),
("do", "r#do"),
("final", "r#final"),
("macro", "r#macro"),
("override", "r#override"),
("priv", "r#priv"),
("typeof", "r#typeof"),
("unsized", "r#unsized"),
("virtual", "r#virtual"),
("yield", "r#yield"),
("try", "r#try"),
];
fn normalize_identifier(ident: &str) -> &str {
if let Some(word) = USE_RAW.iter().find(|x| x.0 == ident) {
word.1
} else {
ident
}
}
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