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use std::borrow;
use std::collections::HashMap;
use std::sync;
use error::{Error, Result};
use value::{Object, Path, Value};
use super::Expression;
use super::Globals;
use super::{BoxedValueFilter, FilterValue};
pub fn unexpected_value_error<S: ToString>(expected: &str, actual: Option<S>) -> Error {
let actual = actual.map(|x| x.to_string());
unexpected_value_error_string(expected, actual)
}
fn unexpected_value_error_string(expected: &str, actual: Option<String>) -> Error {
let actual = actual.unwrap_or_else(|| "nothing".to_owned());
Error::with_msg(format!("Expected {}, found `{}`", expected, actual))
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Interrupt {
Continue,
Break,
}
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct InterruptState {
interrupt: Option<Interrupt>,
}
impl InterruptState {
pub fn interrupted(&self) -> bool {
self.interrupt.is_some()
}
pub fn set_interrupt(&mut self, interrupt: Interrupt) {
self.interrupt = Some(interrupt);
}
pub fn pop_interrupt(&mut self) -> Option<Interrupt> {
let rval = self.interrupt;
self.interrupt = None;
rval
}
}
#[derive(Debug, Clone, PartialEq, Eq, Default)]
struct CycleStateInner {
cycles: HashMap<String, usize>,
}
impl CycleStateInner {
fn cycle_index(&mut self, name: &str, max: usize) -> usize {
let i = self.cycles.entry(name.to_owned()).or_insert(0);
let j = *i;
*i = (*i + 1) % max;
j
}
}
pub struct CycleState<'a, 'g>
where
'g: 'a,
{
context: &'a mut Context<'g>,
}
impl<'a, 'g> CycleState<'a, 'g> {
pub fn cycle_element(&mut self, name: &str, values: &[Expression]) -> Result<Value> {
let index = self.context.cycles.cycle_index(name, values.len());
if index >= values.len() {
return Err(Error::with_msg(
"cycle index out of bounds, most likely from mismatched cycles",
).context("index", format!("{}", index))
.context("count", format!("{}", values.len())));
}
let val = values[index].evaluate(self.context)?;
Ok(val)
}
}
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct IfChangedState {
last_rendered: Option<String>,
}
impl IfChangedState {
pub fn has_changed(&mut self, rendered: &str) -> bool {
let has_changed = if let Some(last_rendered) = &self.last_rendered {
last_rendered != rendered
} else {
true
};
self.last_rendered = Some(rendered.to_owned());
has_changed
}
}
#[derive(Debug, Clone)]
pub struct Stack<'g> {
globals: Option<&'g Globals>,
stack: Vec<Object>,
indexes: Object,
}
impl<'g> Stack<'g> {
pub fn empty() -> Self {
Self {
globals: None,
indexes: Object::new(),
stack: vec![Object::new()],
}
}
pub fn with_globals(globals: &'g Globals) -> Self {
let mut stack = Self::empty();
stack.globals = Some(globals);
stack
}
fn push_frame(&mut self) {
self.stack.push(Object::new());
}
fn pop_frame(&mut self) {
if self.stack.pop().is_none() {
panic!("Pop leaves empty stack")
};
}
pub fn get(&self, path: &Path) -> Result<&Value> {
let mut indexes = path.iter();
let key = indexes
.next()
.ok_or_else(|| Error::with_msg("No variable provided"))?;
let key = key.to_str();
let value = self.get_root(key.as_ref())?;
indexes.fold(Ok(value), |value, index| {
let value = value?;
let child = value.get(index);
let child = child.ok_or_else(|| {
Error::with_msg("Unknown index")
.context("variable", format!("{}", path))
.context("index", format!("{}", index))
})?;
Ok(child)
})
}
fn get_root<'a>(&'a self, name: &str) -> Result<&'a Value> {
for frame in self.stack.iter().rev() {
if let Some(rval) = frame.get(name) {
return Ok(rval);
}
}
self.globals
.ok_or_else(|| Error::with_msg("Unknown variable").context("variable", name.to_owned()))
.and_then(|g| g.get(name))
.or_else(|err| self.get_index(name).ok_or_else(|| err))
}
pub fn set_index<S>(&mut self, name: S, val: Value) -> Option<Value>
where
S: Into<borrow::Cow<'static, str>>,
{
self.indexes.insert(name.into(), val)
}
pub fn get_index<'a>(&'a self, name: &str) -> Option<&'a Value> {
self.indexes.get(name)
}
pub fn set_global<S>(&mut self, name: S, val: Value) -> Option<Value>
where
S: Into<borrow::Cow<'static, str>>,
{
self.global_frame().insert(name.into(), val)
}
pub fn set<S>(&mut self, name: S, val: Value) -> Option<Value>
where
S: Into<borrow::Cow<'static, str>>,
{
self.current_frame().insert(name.into(), val)
}
fn current_frame(&mut self) -> &mut Object {
match self.stack.last_mut() {
Some(frame) => frame,
None => panic!("Global frame removed."),
}
}
fn global_frame(&mut self) -> &mut Object {
match self.stack.first_mut() {
Some(frame) => frame,
None => panic!("Global frame removed."),
}
}
}
impl<'g> Default for Stack<'g> {
fn default() -> Self {
Self::empty()
}
}
pub struct ContextBuilder<'g> {
globals: Option<&'g Globals>,
filters: sync::Arc<HashMap<&'static str, BoxedValueFilter>>,
}
impl<'g> ContextBuilder<'g> {
pub fn new() -> Self {
Self {
globals: None,
filters: Default::default(),
}
}
pub fn set_globals(mut self, values: &'g Globals) -> Self {
self.globals = Some(values);
self
}
pub fn set_filters(
mut self,
filters: &sync::Arc<HashMap<&'static str, BoxedValueFilter>>,
) -> Self {
self.filters = sync::Arc::clone(filters);
self
}
pub fn build(self) -> Context<'g> {
let stack = match self.globals {
Some(globals) => Stack::with_globals(globals),
None => Stack::empty(),
};
Context {
stack,
interrupt: InterruptState::default(),
cycles: CycleStateInner::default(),
ifchanged: IfChangedState::default(),
filters: self.filters,
}
}
}
impl<'g> Default for ContextBuilder<'g> {
fn default() -> Self {
Self::new()
}
}
#[derive(Default)]
pub struct Context<'g> {
stack: Stack<'g>,
interrupt: InterruptState,
cycles: CycleStateInner,
ifchanged: IfChangedState,
filters: sync::Arc<HashMap<&'static str, BoxedValueFilter>>,
}
impl<'g> Context<'g> {
pub fn new() -> Self {
Context::default()
}
pub fn get_filter<'b>(&'b self, name: &str) -> Option<&'b FilterValue> {
self.filters.get(name).map(|f| {
let f: &FilterValue = f;
f
})
}
pub fn interrupt(&self) -> &InterruptState {
&self.interrupt
}
pub fn interrupt_mut(&mut self) -> &mut InterruptState {
&mut self.interrupt
}
pub fn cycles<'a>(&'a mut self) -> CycleState<'a, 'g>
where
'g: 'a,
{
CycleState { context: self }
}
pub fn ifchanged(&mut self) -> &mut IfChangedState {
&mut self.ifchanged
}
pub fn stack(&self) -> &Stack {
&self.stack
}
pub fn stack_mut<'a>(&'a mut self) -> &'a mut Stack<'g>
where
'g: 'a,
{
&mut self.stack
}
pub fn run_in_scope<RvalT, FnT>(&mut self, f: FnT) -> RvalT
where
FnT: FnOnce(&mut Context) -> RvalT,
{
self.stack.push_frame();
let result = f(self);
self.stack.pop_frame();
result
}
}
#[cfg(test)]
mod test {
use super::*;
use value::Scalar;
#[test]
fn stack_get_root() {
let mut ctx = Context::new();
ctx.stack_mut().set_global("number", Value::scalar(42f64));
assert_eq!(
ctx.stack().get_root("number").unwrap(),
&Value::scalar(42f64)
);
}
#[test]
fn stack_get_root_failure() {
let mut ctx = Context::new();
let mut post = Object::new();
post.insert("number".into(), Value::scalar(42f64));
ctx.stack_mut().set_global("post", Value::Object(post));
assert!(ctx.stack().get_root("post.number").is_err());
}
#[test]
fn stack_get() {
let mut ctx = Context::new();
let mut post = Object::new();
post.insert("number".into(), Value::scalar(42f64));
ctx.stack_mut().set_global("post", Value::Object(post));
let indexes = vec![Scalar::new("post"), Scalar::new("number")]
.into_iter()
.collect();
assert_eq!(ctx.stack().get(&indexes).unwrap(), &Value::scalar(42f64));
}
#[test]
fn scoped_variables() {
let mut ctx = Context::new();
ctx.stack_mut().set_global("test", Value::scalar(42f64));
assert_eq!(ctx.stack().get_root("test").unwrap(), &Value::scalar(42f64));
ctx.run_in_scope(|new_scope| {
assert_eq!(
new_scope.stack().get_root("test").unwrap(),
&Value::scalar(42f64)
);
new_scope.stack_mut().set("test", Value::scalar(3.14f64));
assert_eq!(
new_scope.stack().get_root("test").unwrap(),
&Value::scalar(3.14f64)
);
new_scope
.stack_mut()
.set_global("global", Value::scalar("some value"));
});
assert_eq!(ctx.stack().get_root("test").unwrap(), &Value::scalar(42f64));
assert_eq!(
ctx.stack().get_root("global").unwrap(),
&Value::scalar("some value")
);
}
}