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//! Block helper that iterates arrays and objects.
use crate::{
//error::HelperError,
helper::{Helper, HelperValue},
parser::ast::Node,
render::{Context, Render, Scope},
};
use serde_json::{Number, Value};
const FIRST: &str = "first";
const LAST: &str = "last";
const KEY: &str = "key";
const INDEX: &str = "index";
/// Iterate an array or object.
///
/// Accepts a single argument of the target to iterate, if the
/// target is not an array or object this will return an error.
///
/// Each iteration sets a new scope with the local variables:
///
/// * `@first`: If this is the first iteration `true`.
/// * `@last`: If this is the last iteration `true`.
///
/// Note that these variables are set even for objects where iteration order
/// is not guaranteed which can be useful.
///
/// For objects the `@key` variable contains the name of the field; for
/// arrays the `@index` variable contains the current zero-based index.
///
pub struct Each;
impl Helper for Each {
fn call<'render, 'call>(
&self,
rc: &mut Render<'render>,
ctx: &Context<'call>,
template: Option<&'render Node<'render>>,
) -> HelperValue {
ctx.arity(1..1)?;
if let Some(template) = template {
//let name = ctx.name();
let args = ctx.arguments();
let target = args.get(0).unwrap();
rc.push_scope(Scope::new());
match target {
Value::Object(t) => {
let mut it = t.into_iter().enumerate();
let mut next_value = it.next();
while let Some((index, (key, value))) = next_value {
next_value = it.next();
if let Some(ref mut scope) = rc.scope_mut() {
scope.set_local(FIRST, Value::Bool(index == 0));
scope.set_local(
LAST,
Value::Bool(next_value.is_none()),
);
scope.set_local(
INDEX,
Value::Number(Number::from(index)),
);
scope.set_local(KEY, Value::String(key.to_owned()));
scope.set_base_value(value.clone());
}
rc.template(template)?;
}
}
Value::Array(t) => {
let len = t.len();
for (index, value) in t.into_iter().enumerate() {
if let Some(ref mut scope) = rc.scope_mut() {
scope.set_local(FIRST, Value::Bool(index == 0));
scope
.set_local(LAST, Value::Bool(index == len - 1));
scope.set_local(
INDEX,
Value::Number(Number::from(index)),
);
scope.set_base_value(value.clone());
}
rc.template(template)?;
}
}
_ => {
//return Err(HelperError::IterableExpected(
//name.to_string(),
//0,
//))
}
}
rc.pop_scope();
}
Ok(None)
}
}