handlebars/
block.rs

1use std::collections::BTreeMap;
2
3use serde_json::value::Value as Json;
4
5use crate::error::RenderError;
6use crate::local_vars::LocalVars;
7
8#[derive(Clone, Debug)]
9pub enum BlockParamHolder {
10    // a reference to certain context value
11    Path(Vec<String>),
12    // an actual value holder
13    Value(Json),
14}
15
16impl BlockParamHolder {
17    pub fn value(v: Json) -> BlockParamHolder {
18        BlockParamHolder::Value(v)
19    }
20
21    pub fn path(r: Vec<String>) -> BlockParamHolder {
22        BlockParamHolder::Path(r)
23    }
24}
25
26/// A map holds block parameters. The parameter can be either a value or a reference
27#[derive(Clone, Debug, Default)]
28pub struct BlockParams<'reg> {
29    data: BTreeMap<&'reg str, BlockParamHolder>,
30}
31
32impl<'reg> BlockParams<'reg> {
33    /// Create a empty block parameter map.
34    pub fn new() -> BlockParams<'reg> {
35        BlockParams::default()
36    }
37
38    /// Add a path reference as the parameter. The `path` is a vector of path
39    /// segments the relative to current block's base path.
40    pub fn add_path(&mut self, k: &'reg str, path: Vec<String>) -> Result<(), RenderError> {
41        self.data.insert(k, BlockParamHolder::path(path));
42        Ok(())
43    }
44
45    /// Add a value as parameter.
46    pub fn add_value(&mut self, k: &'reg str, v: Json) -> Result<(), RenderError> {
47        self.data.insert(k, BlockParamHolder::value(v));
48        Ok(())
49    }
50
51    /// Get a block parameter by its name.
52    pub fn get(&self, k: &str) -> Option<&BlockParamHolder> {
53        self.data.get(k)
54    }
55}
56
57/// A data structure holds contextual data for current block scope.
58#[derive(Debug, Clone, Default)]
59pub struct BlockContext<'rc> {
60    /// the `base_path` of current block scope
61    base_path: Vec<String>,
62    /// the `base_value` of current block scope, when the block is using a
63    /// constant or derived value as block base
64    base_value: Option<Json>,
65    /// current block context variables
66    block_params: BlockParams<'rc>,
67    /// local variables in current context
68    local_variables: LocalVars,
69}
70
71impl<'rc> BlockContext<'rc> {
72    /// create a new `BlockContext` with default data
73    pub fn new() -> BlockContext<'rc> {
74        BlockContext::default()
75    }
76
77    /// set a local variable into current scope
78    pub fn set_local_var(&mut self, name: &str, value: Json) {
79        self.local_variables.put(name, value);
80    }
81
82    /// Get mutable access to the local variables
83    pub fn local_variables_mut(&mut self) -> &mut LocalVars {
84        &mut self.local_variables
85    }
86
87    /// get a local variable from current scope
88    pub fn get_local_var(&self, name: &str) -> Option<&Json> {
89        self.local_variables.get(name)
90    }
91
92    /// borrow a reference to current scope's base path
93    /// all paths inside this block will be relative to this path
94    pub fn base_path(&self) -> &Vec<String> {
95        &self.base_path
96    }
97
98    /// borrow a mutable reference to the base path
99    pub fn base_path_mut(&mut self) -> &mut Vec<String> {
100        &mut self.base_path
101    }
102
103    /// borrow the base value
104    pub fn base_value(&self) -> Option<&Json> {
105        self.base_value.as_ref()
106    }
107
108    /// set the base value
109    pub fn set_base_value(&mut self, value: Json) {
110        self.base_value = Some(value);
111    }
112
113    /// Get a block parameter from this block.
114    /// Block parameters needed to be supported by the block helper.
115    /// The typical syntax for block parameter is:
116    ///
117    /// ```skip
118    /// {{#myblock param1 as |block_param1|}}
119    ///    ...
120    /// {{/myblock}}
121    /// ```
122    ///
123    pub fn get_block_param(&self, block_param_name: &str) -> Option<&BlockParamHolder> {
124        self.block_params.get(block_param_name)
125    }
126
127    /// Reassign the block parameters for this block.
128    pub fn set_block_params(&mut self, block_params: BlockParams<'rc>) {
129        self.block_params = block_params;
130    }
131
132    /// Set a block parameter into this block.
133    pub fn set_block_param(&mut self, key: &'rc str, value: BlockParamHolder) {
134        self.block_params.data.insert(key, value);
135    }
136}
handlebars/block.rs

handlebars/
block.rs
