1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165

use std::collections::HashMap;
use std::fmt;
use std::sync;

use crate::compiler;
use crate::compiler::Language;
use crate::error::Result;
use crate::interpreter;
use crate::interpreter::PartialStore;
use crate::interpreter::Renderable;

use super::PartialCompiler;
use super::PartialSource;

/// An lazily-caching compiler for `PartialSource`.
///
/// This would be useful in cases where:
/// - Most partial-templates aren't used
/// - Of the used partial-templates, they are generally used many times.
///
/// Note: partial-compilation error reporting is deferred to render-time so content can still be
/// generated even when the content is in an intermediate-state.
#[derive(Debug)]
pub struct LazyCompiler<S: PartialSource> {
    source: S,
}

impl<S> LazyCompiler<S>
where
    S: PartialSource,
{
    /// Create an on-demand compiler for `PartialSource`.
    pub fn new(source: S) -> Self {
        LazyCompiler { source }
    }
}

impl<S> LazyCompiler<S>
where
    S: PartialSource + Default,
{
    /// Create an empty compiler for `PartialSource`.
    pub fn empty() -> Self {
        Default::default()
    }
}

impl<S> Default for LazyCompiler<S>
where
    S: PartialSource + Default,
{
    fn default() -> Self {
        Self {
            source: Default::default(),
        }
    }
}

impl<S> ::std::ops::Deref for LazyCompiler<S>
where
    S: PartialSource,
{
    type Target = S;

    fn deref(&self) -> &S {
        &self.source
    }
}

impl<S> ::std::ops::DerefMut for LazyCompiler<S>
where
    S: PartialSource,
{
    fn deref_mut(&mut self) -> &mut S {
        &mut self.source
    }
}

impl<S> PartialCompiler for LazyCompiler<S>
where
    S: PartialSource + Send + Sync + 'static,
{
    fn compile(self, language: sync::Arc<Language>) -> Result<Box<dyn PartialStore + Send + Sync>> {
        let store = LazyStore {
            language,
            source: self.source,
            cache: sync::Mutex::new(Default::default()),
        };
        Ok(Box::new(store))
    }

    fn source(&self) -> &dyn PartialSource {
        &self.source
    }
}

struct LazyStore<S: PartialSource> {
    language: sync::Arc<Language>,
    source: S,
    cache: sync::Mutex<HashMap<String, Result<sync::Arc<dyn interpreter::Renderable>>>>,
}

impl<S> LazyStore<S>
where
    S: PartialSource,
{
    fn try_get_or_create(&self, name: &str) -> Option<sync::Arc<dyn Renderable>> {
        let cache = self.cache.lock().expect("not to be poisoned and reused");
        if let Some(result) = cache.get(name) {
            result.as_ref().ok().cloned()
        } else {
            let s = self.source.try_get(name)?;
            let s = s.as_ref();
            let template = compiler::parse(s, &self.language)
                .map(interpreter::Template::new)
                .map(sync::Arc::new)
                .ok()?;
            Some(template)
        }
    }

    fn get_or_create(&self, name: &str) -> Result<sync::Arc<dyn Renderable>> {
        let cache = self.cache.lock().expect("not to be poisoned and reused");
        if let Some(result) = cache.get(name) {
            result.clone()
        } else {
            let s = self.source.get(name)?;
            let s = s.as_ref();
            let template = compiler::parse(s, &self.language)
                .map(interpreter::Template::new)
                .map(sync::Arc::new)?;
            Ok(template)
        }
    }
}

impl<S> PartialStore for LazyStore<S>
where
    S: PartialSource,
{
    fn contains(&self, name: &str) -> bool {
        self.source.contains(name)
    }

    fn names(&self) -> Vec<&str> {
        self.source.names()
    }

    fn try_get(&self, name: &str) -> Option<sync::Arc<dyn Renderable>> {
        self.try_get_or_create(name)
    }

    fn get(&self, name: &str) -> Result<sync::Arc<dyn Renderable>> {
        self.get_or_create(name)
    }
}

impl<S> fmt::Debug for LazyStore<S>
where
    S: PartialSource,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.source.fmt(f)
    }
}