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environment.rs
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environment.rs
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use std::collections::BTreeMap;
use std::fmt;
use std::sync::Arc;
use serde::Serialize;
use crate::compiler::codegen::CodeGenerator;
use crate::compiler::parser::parse_expr;
use crate::error::{attach_basic_debug_info, Error};
use crate::expression::Expression;
use crate::output::Output;
use crate::template::{CompiledTemplate, Template};
use crate::utils::{AutoEscape, BTreeMapKeysDebug};
use crate::value::{ArgType, FunctionArgs, FunctionResult, Value};
use crate::vm::Vm;
use crate::{defaults, filters, functions, tests};
type TemplateMap<'source> = BTreeMap<&'source str, Arc<CompiledTemplate<'source>>>;
#[derive(Clone)]
enum Source<'source> {
Borrowed(TemplateMap<'source>),
#[cfg(feature = "source")]
Owned(crate::source::Source),
}
impl<'source> fmt::Debug for Source<'source> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Borrowed(tmpls) => fmt::Debug::fmt(&BTreeMapKeysDebug(tmpls), f),
#[cfg(feature = "source")]
Self::Owned(arg0) => fmt::Debug::fmt(arg0, f),
}
}
}
type AutoEscapeFunc = dyn Fn(&str) -> AutoEscape + Sync + Send;
type FormatterFunc = dyn Fn(&mut Output, &Value) -> Result<(), Error> + Sync + Send;
/// An abstraction that holds the engine configuration.
///
/// This object holds the central configuration state for templates. It is also
/// the container for all loaded templates.
///
/// The environment holds references to the source the templates were created from.
/// This makes it very inconvenient to pass around unless the templates are static
/// strings.
#[cfg_attr(
feature = "source",
doc = "
For situations where you want to load dynamic templates and share the
environment it's recommended to turn on the `source` feature and to use the
[`Source`](crate::source::Source) type with the environment."
)]
///
/// There are generally two ways to construct an environment:
///
/// * [`Environment::new`] creates an environment preconfigured with sensible
/// defaults. It will contain all built-in filters, tests and globals as well
/// as a callback for auto escaping based on file extension.
/// * [`Environment::empty`] creates a completely blank environment.
#[derive(Clone)]
pub struct Environment<'source> {
templates: Source<'source>,
filters: BTreeMap<&'source str, filters::BoxedFilter>,
tests: BTreeMap<&'source str, tests::BoxedTest>,
pub(crate) globals: BTreeMap<&'source str, Value>,
default_auto_escape: Arc<AutoEscapeFunc>,
formatter: Arc<FormatterFunc>,
#[cfg(feature = "debug")]
debug: bool,
}
impl<'source> Default for Environment<'source> {
fn default() -> Self {
Environment::empty()
}
}
impl<'source> fmt::Debug for Environment<'source> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Environment")
.field("globals", &self.globals)
.field("tests", &BTreeMapKeysDebug(&self.tests))
.field("filters", &BTreeMapKeysDebug(&self.filters))
.field("templates", &self.templates)
.finish()
}
}
impl<'source> Environment<'source> {
/// Creates a new environment with sensible defaults.
///
/// This environment does not yet contain any templates but it will have all
/// the default filters, tests and globals loaded. If you do not want any
/// default configuration you can use the alternative
/// [`empty`](Environment::empty) method.
pub fn new() -> Environment<'source> {
Environment {
templates: Source::Borrowed(Default::default()),
filters: defaults::get_builtin_filters(),
tests: defaults::get_builtin_tests(),
globals: defaults::get_globals(),
default_auto_escape: Arc::new(defaults::default_auto_escape_callback),
formatter: Arc::new(defaults::escape_formatter),
#[cfg(feature = "debug")]
debug: cfg!(debug_assertions),
}
}
/// Creates a completely empty environment.
///
/// This environment has no filters, no templates, no globals and no default
/// logic for auto escaping configured.
pub fn empty() -> Environment<'source> {
Environment {
templates: Source::Borrowed(Default::default()),
filters: Default::default(),
tests: Default::default(),
globals: Default::default(),
default_auto_escape: Arc::new(defaults::no_auto_escape),
formatter: Arc::new(defaults::escape_formatter),
#[cfg(feature = "debug")]
debug: cfg!(debug_assertions),
}
}
/// Loads a template from a string.
///
/// The `name` parameter defines the name of the template which identifies
/// it. To look up a loaded template use the [`get_template`](Self::get_template)
/// method.
///
/// Note that there are situations where the interface of this method is
/// too restrictive. For instance the environment itself does not permit
/// any form of sensible dynamic template loading.
#[cfg_attr(
feature = "source",
doc = "To address this restriction use [`set_source`](Self::set_source)."
)]
pub fn add_template(&mut self, name: &'source str, source: &'source str) -> Result<(), Error> {
match self.templates {
Source::Borrowed(ref mut map) => {
let compiled_template = CompiledTemplate::from_name_and_source(name, source)?;
map.insert(name, Arc::new(compiled_template));
Ok(())
}
#[cfg(feature = "source")]
Source::Owned(ref mut src) => src.add_template(name, source),
}
}
/// Removes a template by name.
pub fn remove_template(&mut self, name: &str) {
match self.templates {
Source::Borrowed(ref mut map) => {
map.remove(name);
}
#[cfg(feature = "source")]
Source::Owned(ref mut source) => {
source.remove_template(name);
}
}
}
/// Fetches a template by name.
///
/// This requires that the template has been loaded with
/// [`add_template`](Environment::add_template) beforehand. If the template was
/// not loaded an error of kind `TemplateNotFound` is returned.
///
/// ```
/// # use minijinja::{Environment, context};
/// let mut env = Environment::new();
/// env.add_template("hello.txt", "Hello {{ name }}!").unwrap();
/// let tmpl = env.get_template("hello.txt").unwrap();
/// println!("{}", tmpl.render(context!{ name => "World" }).unwrap());
/// ```
pub fn get_template(&self, name: &str) -> Result<Template<'_>, Error> {
let compiled = match &self.templates {
Source::Borrowed(ref map) => map.get(name).ok_or_else(|| Error::new_not_found(name))?,
#[cfg(feature = "source")]
Source::Owned(source) => source.get_compiled_template(name)?,
};
Ok(Template::new(
self,
compiled,
self.get_initial_auto_escape(name),
))
}
/// Parses and renders a template from a string in one go.
///
/// In some cases you really only need a template to be rendered once from
/// a string and returned. The internal name of the template is `<string>`.
///
/// ```
/// # use minijinja::{Environment, context};
/// let env = Environment::new();
/// let rv = env.render_str("Hello {{ name }}", context! { name => "World" });
/// println!("{}", rv.unwrap());
/// ```
pub fn render_str<S: Serialize>(&self, source: &str, 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_str(source, Value::from_serializable(&ctx))
}
fn _render_str(&self, source: &str, root: Value) -> Result<String, Error> {
let name = "<string>";
let compiled = CompiledTemplate::from_name_and_source(name, source)?;
let mut rv = String::new();
Vm::new(self)
.eval(
&compiled.instructions,
root,
&compiled.blocks,
&mut Output::with_string(&mut rv, self.get_initial_auto_escape(name)),
)
.map(|_| rv)
}
/// Sets a new function to select the default auto escaping.
///
/// This function is invoked when templates are loaded from the environment
/// to determine the default auto escaping behavior. The function is
/// invoked with the name of the template and can make an initial auto
/// escaping decision based on that. The default implementation
/// ([`default_auto_escape_callback`](defaults::default_auto_escape_callback))
/// turn on escaping depending on the file extension.
///
/// ```
/// # use minijinja::{Environment, AutoEscape};
/// # let mut env = Environment::new();
/// env.set_auto_escape_callback(|name| {
/// if matches!(name.rsplit('.').next().unwrap_or(""), "html" | "htm" | "aspx") {
/// AutoEscape::Html
/// } else {
/// AutoEscape::None
/// }
/// });
/// ```
pub fn set_auto_escape_callback<F>(&mut self, f: F)
where
F: Fn(&str) -> AutoEscape + 'static + Sync + Send,
{
self.default_auto_escape = Arc::new(f);
}
/// Sets a different formatter function.
///
/// The formatter is invoked to format the given value into the provided
/// [`Output`]. The default implementation is
/// [`escape_formatter`](defaults::escape_formatter).
///
/// When implementing a custom formatter it depends on if auto escaping
/// should be supported or not. If auto escaping should be supported then
/// it's easiest to just wrap the default formatter. The
/// following example swaps out `None` values before rendering for
/// `Undefined` which renders as an empty string instead.
///
/// The current value of the auto escape flag can be retrieved directly
/// from the output with [`Output::auto_escape`].
///
/// ```
/// # use minijinja::Environment;
/// # let mut env = Environment::new();
/// use minijinja::escape_formatter;
/// use minijinja::value::Value;
///
/// env.set_formatter(|out, value| {
/// escape_formatter(
/// out,
/// if value.is_none() {
/// &Value::UNDEFINED
/// } else {
/// value
/// },
/// )
///});
/// # assert_eq!(env.render_str("{{ none }}", ()).unwrap(), "");
/// ```
pub fn set_formatter<F>(&mut self, f: F)
where
F: Fn(&mut Output, &Value) -> Result<(), Error> + 'static + Sync + Send,
{
self.formatter = Arc::new(f);
}
/// Enable or disable the debug mode.
///
/// When the debug mode is enabled the engine will dump out some of the
/// execution state together with the source information of the executing
/// template when an error is created. The cost of this is relatively
/// high as the data including the template source is cloned.
///
/// When this is enabled templates will print debug information with source
/// context when the error is printed.
///
/// This requires the `debug` feature. This is enabled by default if
/// debug assertions are enabled and false otherwise.
#[cfg(feature = "debug")]
#[cfg_attr(docsrs, doc(cfg(feature = "debug")))]
pub fn set_debug(&mut self, enabled: bool) {
self.debug = enabled;
}
#[cfg(feature = "debug")]
pub(crate) fn debug(&self) -> bool {
self.debug
}
/// Sets the template source for the environment.
///
/// This helps when working with dynamically loaded templates. The
/// [`Source`](crate::source::Source) is consulted by the environment to
/// look up templates that are requested. The source has the capabilities
/// to load templates with fewer lifetime restrictions and can also
/// load templates dynamically at runtime as requested.
///
/// When a source is set already loaded templates in the environment are
/// discarded and replaced with the templates from the source.
///
/// For more information see [`Source`](crate::source::Source).
#[cfg(feature = "source")]
#[cfg_attr(docsrs, doc(cfg(feature = "source")))]
pub fn set_source(&mut self, source: crate::source::Source) {
self.templates = Source::Owned(source);
}
/// Returns the currently set source.
#[cfg(feature = "source")]
#[cfg_attr(docsrs, doc(cfg(feature = "source")))]
pub fn source(&self) -> Option<&crate::source::Source> {
match self.templates {
Source::Borrowed(_) => None,
Source::Owned(ref source) => Some(source),
}
}
/// Compiles an expression.
///
/// This lets one compile an expression in the template language and
/// receive the output. This lets one use the expressions of the language
/// be used as a minimal scripting language. For more information and an
/// example see [`Expression`].
pub fn compile_expression(&self, expr: &'source str) -> Result<Expression<'_, 'source>, Error> {
attach_basic_debug_info(self._compile_expression(expr), expr)
}
fn _compile_expression(&self, expr: &'source str) -> Result<Expression<'_, 'source>, Error> {
let ast = parse_expr(expr)?;
let mut compiler = CodeGenerator::new("<expression>", expr);
compiler.compile_expr(&ast)?;
let (instructions, _) = compiler.finish();
Ok(Expression::new(self, instructions))
}
/// Adds a new filter function.
///
/// Filter functions are functions that can be applied to values in
/// templates. For details about filters have a look at
/// [`Filter`](crate::filters::Filter).
pub fn add_filter<F, Rv, Args>(&mut self, name: &'source str, f: F)
where
// the crazy bounds here exist to enable borrowing in closures
F: filters::Filter<Rv, Args>
+ for<'a> filters::Filter<Rv, <Args as FunctionArgs<'a>>::Output>,
Rv: FunctionResult,
Args: for<'a> FunctionArgs<'a>,
{
self.filters.insert(name, filters::BoxedFilter::new(f));
}
/// Removes a filter by name.
pub fn remove_filter(&mut self, name: &str) {
self.filters.remove(name);
}
/// Adds a new test function.
///
/// Test functions are similar to filters but perform a check on a value
/// where the return value is always true or false. For details about tests
/// have a look at [`Test`](crate::tests::Test).
pub fn add_test<F, Rv, V, Args>(&mut self, name: &'source str, f: F)
where
// the crazy bounds here exist to enable borrowing in closures
F: tests::Test<Rv, V, Args>
+ for<'a> tests::Test<Rv, <V as ArgType<'a>>::Output, <Args as FunctionArgs<'a>>::Output>,
Rv: tests::TestResult,
V: for<'a> ArgType<'a>,
Args: for<'a> FunctionArgs<'a>,
{
self.tests.insert(name, tests::BoxedTest::new(f));
}
/// Removes a test by name.
pub fn remove_test(&mut self, name: &str) {
self.tests.remove(name);
}
/// Adds a new global function.
///
/// For details about functions have a look at [`functions`]. Note that
/// functions and other global variables share the same namespace.
/// For more details about functions have a look at
/// [`Function`](crate::functions::Function).
pub fn add_function<F, Rv, Args>(&mut self, name: &'source str, f: F)
where
// the crazy bounds here exist to enable borrowing in closures
F: functions::Function<Rv, Args>
+ for<'a> functions::Function<Rv, <Args as FunctionArgs<'a>>::Output>,
Rv: FunctionResult,
Args: for<'a> FunctionArgs<'a>,
{
self.add_global(name, functions::BoxedFunction::new(f).to_value());
}
/// Adds a global variable.
pub fn add_global(&mut self, name: &'source str, value: Value) {
self.globals.insert(name, value);
}
/// Removes a global function or variable by name.
pub fn remove_global(&mut self, name: &str) {
self.globals.remove(name);
}
/// Looks up a function.
pub(crate) fn get_global(&self, name: &str) -> Option<Value> {
self.globals.get(name).cloned()
}
/// Looks up a filter.
pub(crate) fn get_filter(&self, name: &str) -> Option<&filters::BoxedFilter> {
self.filters.get(name)
}
/// Looks up a test function.
pub(crate) fn get_test(&self, name: &str) -> Option<&tests::BoxedTest> {
self.tests.get(name)
}
pub(crate) fn get_initial_auto_escape(&self, name: &str) -> AutoEscape {
(self.default_auto_escape)(name)
}
/// Formats a value into the final format.
///
/// This step is called finalization in Jinja2 but since we are writing into
/// the output stream rather than converting values, it's renamed to format
/// here.
pub(crate) fn format(&self, value: &Value, out: &mut Output) -> Result<(), Error> {
(self.formatter)(out, value)
}
}