Text Placeholder

A flexible text template engine that allows templates with named placeholders within it.

Placeholders are defined by default following the handlebars syntax, but can be overriden with specific boundaries.

In order to provide the context in which our placeholders will be replaced the following options are available:

• HashMap
• Struct as an optional feature.

HashMap

As the name implies we can pass a HashMap in order to provide the context. The methods available are:

• fill_with_hashmap which replaces empty placeholders with an empty string.
• fill_with_hashmap_strict which returns a Error::PlaceholderError when:
  • the provided context does not contain the placeholder
  • the provided value for a placeholder cannot be converted to a string

Example

use text_placeholder::Template;
use std::collections::HashMap;

let default_template = Template::new("Hello {{first}} {{second}}!");

let mut table = HashMap::new();
table.insert("first", "text");
table.insert("second", "placeholder");

assert_eq!(default_template.fill_with_hashmap(&table), "Hello text placeholder!");

// We can also specify our own boundaries:

let custom_template = Template::new_with_placeholder("Hello $[first]] $[second]!", "$[", "]");

assert_eq!(default_template.fill_with_hashmap(&table), "Hello text placeholder!");

Struct

This is an optional feature that depends on serde. In order to enable it specify in your Cargo.toml dependencies the following:

text_placeholder = { version = "0.2", features = ["struct_context"] }

As the name implies we can pass a Struct in order that implements the serde::Serialize trait in order to provide the context. The methods available are:

• fill_with_struct which replaces empty placeholders with an empty string.
• fill_with_struct_strict which returns a Error::PlaceholderError when:
  • the provided context does not contain the placeholder
  • the provided value for a placeholder cannot be converted to a string

Example

use text_placeholder::Template;

#[derive(Serialize)]
struct Context {
    first: String,
    second: String
}

let default_template = Template::new("Hello {{first}} {{second}}!");
let context = Context { first: "text".to_string(), second: "placeholder".to_string() };

assert_eq!(default_template.fill_with_struct(&context), "Hello text placeholder!");

// We can also specify our own boundaries:

let custom_template = Template::new_with_placeholder("Hello $[first]] $[second]!", "$[", "]");

assert_eq!(default_template.fill_with_struct(&context), "Hello text placeholder!");

Roadmap

• Allow objects that implement trait std::ops::Index instead of depending directly on a HashMap.