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template.rs
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template.rs
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use std::collections::BTreeMap;
use std::{fmt, io};
use serde::Serialize;
use crate::compiler::codegen::CodeGenerator;
use crate::compiler::instructions::Instructions;
use crate::compiler::parser::parse;
use crate::environment::Environment;
use crate::error::{attach_basic_debug_info, Error, ErrorKind};
use crate::output::{Output, WriteWrapper};
use crate::utils::AutoEscape;
use crate::value::Value;
use crate::vm::Vm;
/// Represents a handle to a template.
///
/// Templates are stored in the [`Environment`] as bytecode instructions. With the
/// [`Environment::get_template`] method that is looked up and returned in form of
/// this handle. Such a template can be cheaply copied as it only holds references.
///
/// To render the [`render`](Template::render) method can be used.
#[derive(Copy, Clone)]
pub struct Template<'env> {
env: &'env Environment<'env>,
compiled: &'env CompiledTemplate<'env>,
initial_auto_escape: AutoEscape,
}
impl<'env> fmt::Debug for Template<'env> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut ds = f.debug_struct("Template");
ds.field("name", &self.name());
#[cfg(feature = "internal_debug")]
{
ds.field("instructions", &self.compiled.instructions);
ds.field("blocks", &self.compiled.blocks);
}
ds.field("initial_auto_escape", &self.initial_auto_escape);
ds.finish()
}
}
impl<'env> Template<'env> {
pub(crate) fn new(
env: &'env Environment<'env>,
compiled: &'env CompiledTemplate<'env>,
initial_auto_escape: AutoEscape,
) -> Template<'env> {
Template {
env,
compiled,
initial_auto_escape,
}
}
/// Returns the name of the template.
pub fn name(&self) -> &str {
self.compiled.instructions.name()
}
/// Returns the source code of the template.
pub fn source(&self) -> &str {
self.compiled.instructions.source()
}
/// Renders the template into a string.
///
/// The provided value is used as the initial context for the template. It
/// can be any object that implements [`Serialize`](serde::Serialize). You
/// can eiher create your own struct and derive `Serialize` for it or the
/// [`context!`](crate::context) macro can be used to create an ad-hoc context.
///
/// ```
/// # use minijinja::{Environment, context};
/// # let mut env = Environment::new();
/// # env.add_template("hello", "Hello {{ name }}!").unwrap();
/// let tmpl = env.get_template("hello").unwrap();
/// println!("{}", tmpl.render(context!(name => "John")).unwrap());
/// ```
pub fn render<S: Serialize>(&self, ctx: S) -> Result<String, Error> {
// reduce total amount of code faling under mono morphization into
// this function, and share the rest in _eval.
self._render(Value::from_serializable(&ctx))
}
fn _render(&self, root: Value) -> Result<String, Error> {
let mut rv = String::new();
self._eval(
root,
&mut Output::with_string(&mut rv, self.initial_auto_escape),
)
.map(|_| rv)
}
/// Renders the template into a [`io::Write`].
///
/// This works exactly like [`render`](Self::render) but instead writes the template
/// as it's evaluating into a [`io::Write`].
///
/// ```
/// # use minijinja::{Environment, context};
/// # let mut env = Environment::new();
/// # env.add_template("hello", "Hello {{ name }}!").unwrap();
/// use std::io::stdout;
///
/// let tmpl = env.get_template("hello").unwrap();
/// tmpl.render_to_write(context!(name => "John"), &mut stdout()).unwrap();
/// ```
pub fn render_to_write<S: Serialize, W: io::Write>(&self, ctx: S, w: W) -> Result<(), Error> {
let mut wrapper = WriteWrapper { w, err: None };
self._eval(
Value::from_serializable(&ctx),
&mut Output::with_write(&mut wrapper, self.initial_auto_escape),
)
.map_err(|err| {
wrapper
.err
.take()
.map(|io_err| {
Error::new(ErrorKind::WriteFailure, "I/O error during rendering")
.with_source(io_err)
})
.unwrap_or(err)
})
}
fn _eval(&self, root: Value, out: &mut Output) -> Result<(), Error> {
Vm::new(self.env)
.eval(
&self.compiled.instructions,
root,
&self.compiled.blocks,
out,
)
.map(|_| ())
}
/// Returns the root instructions.
pub(crate) fn instructions(&self) -> &'env Instructions<'env> {
&self.compiled.instructions
}
/// Returns the blocks.
pub(crate) fn blocks(&self) -> &'env BTreeMap<&'env str, Instructions<'env>> {
&self.compiled.blocks
}
/// Returns the initial auto escape setting.
pub(crate) fn initial_auto_escape(&self) -> AutoEscape {
self.initial_auto_escape
}
}
/// Represents a compiled template in memory.
pub(crate) struct CompiledTemplate<'source> {
pub instructions: Instructions<'source>,
pub blocks: BTreeMap<&'source str, Instructions<'source>>,
}
impl<'env> fmt::Debug for CompiledTemplate<'env> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut ds = f.debug_struct("CompiledTemplate");
#[cfg(feature = "internal_debug")]
{
ds.field("instructions", &self.instructions);
ds.field("blocks", &self.blocks);
}
ds.finish()
}
}
impl<'source> CompiledTemplate<'source> {
pub(crate) fn from_name_and_source(
name: &'source str,
source: &'source str,
) -> Result<CompiledTemplate<'source>, Error> {
attach_basic_debug_info(Self::_from_name_and_source_impl(name, source), source)
}
fn _from_name_and_source_impl(
name: &'source str,
source: &'source str,
) -> Result<CompiledTemplate<'source>, Error> {
let ast = parse(source, name)?;
let mut compiler = CodeGenerator::new(name, source);
compiler.compile_stmt(&ast)?;
let (instructions, blocks) = compiler.finish();
Ok(CompiledTemplate {
blocks,
instructions,
})
}
}