Struct Generator 

pub struct Generator {
    pub pipeline: Pipeline,
    pub ctx: GenContext,
}

Main generator that orchestrates template processing and file generation

Fields

pipeline: Pipeline

ctx: GenContext

Implementations

impl Generator

pub fn new(pipeline: Pipeline, ctx: GenContext) -> Self

Create a new generator with a pipeline and context

Example

use ggen_core::generator::{Generator, GenContext};
use ggen_core::pipeline::Pipeline;
use std::path::PathBuf;

let pipeline = Pipeline::new()?;
let ctx = GenContext::new(
    PathBuf::from("template.tmpl"),
    PathBuf::from("output")
);
let generator = Generator::new(pipeline, ctx);

pub fn generate(&mut self) -> Result<PathBuf>

Generate output from the template

Processes the template, renders it with the provided context, and writes the output to the specified location.

Returns

Returns the path to the generated file. The path is returned even in dry run mode (when dry_run is true), allowing you to preview where the file would be written without actually creating it.

The output path is determined as follows:

• If the template frontmatter specifies a to field, that path is used (rendered with template variables)
• Otherwise, the output path defaults to the template filename with a .out extension in the output root directory

Behavior

• Parent directories: Automatically creates parent directories as needed
• Frozen sections: If the output file already exists and contains frozen sections (marked with # frozen comments), those sections are preserved and merged with the new generated content
• Dry run: When dry_run is true, the file is not written to disk, but the path is still returned

Errors

Returns an error if:

• The template file cannot be read
• The template syntax is invalid
• Template variables are missing or invalid
• RDF processing fails (if RDF is used)
• The template path has no file stem (cannot determine default output name)
• The output file cannot be written (unless in dry run mode)
• File system permissions are insufficient
• Parent directories cannot be created

Examples

Success case

use ggen_core::generator::{Generator, GenContext};
use ggen_core::pipeline::Pipeline;
use std::collections::BTreeMap;
use std::path::PathBuf;

let pipeline = Pipeline::new()?;
let mut vars = BTreeMap::new();
vars.insert("name".to_string(), "MyApp".to_string());

let ctx = GenContext::new(
    PathBuf::from("template.tmpl"),
    PathBuf::from("output")
).with_vars(vars);

let mut generator = Generator::new(pipeline, ctx);
let output_path = generator.generate()?;
println!("Generated: {:?}", output_path);

Error case - Template file not found

use ggen_core::generator::{Generator, GenContext};
use ggen_core::pipeline::Pipeline;
use std::path::PathBuf;

let pipeline = Pipeline::new()?;
let ctx = GenContext::new(
    PathBuf::from("nonexistent.tmpl"), // File doesn't exist
    PathBuf::from("output")
);

let mut generator = Generator::new(pipeline, ctx);
// This will fail because the template file doesn't exist
let result = generator.generate();
assert!(result.is_err());