Struct HeaderInfo 

pub struct HeaderInfo {
    pub version: (u32, u32),
    pub structs: BTreeMap<String, Vec<String>>,
    pub aliases: BTreeMap<String, String>,
    pub nests: BTreeMap<String, Vec<String>>,
    pub null_char: char,
    pub quote_char: char,
    pub count_totals: BTreeMap<String, usize>,
    pub count_fields: BTreeMap<String, BTreeMap<String, usize>>,
}

Header information parsed from the HEDL document.

Contains metadata extracted from header directives:

• %VERSION: Document format version
• %STRUCT: Schema definitions mapping type names to column lists
• %ALIAS: Variable substitutions
• %NEST: Parent-child relationship rules

Examples

use hedl_stream::{StreamingParser, HeaderInfo};
use std::io::Cursor;

let input = r#"
%VERSION: 1.0
%STRUCT: User: [id, name, email]
%ALIAS: admin = "Administrator"
%NEST: User > Order
---
"#;

let parser = StreamingParser::new(Cursor::new(input))?;
let header = parser.header().unwrap();

// Access version
let (major, minor) = header.version;
println!("HEDL version {}.{}", major, minor);

// Look up schema
if let Some(schema) = header.get_schema("User") {
    println!("User has {} fields", schema.len());
}

// Check for alias
if let Some(value) = header.aliases.get("admin") {
    println!("Alias 'admin' expands to '{}'", value);
}

// Check nesting rule
if let Some(children) = header.get_child_types("User") {
    println!("User can contain {:?}", children);
}

Fields

version: (u32, u32)

HEDL version (major, minor).

structs: BTreeMap<String, Vec<String>>

Schema definitions: type -> columns.

aliases: BTreeMap<String, String>

Alias definitions.

nests: BTreeMap<String, Vec<String>>

Nest relationships: parent -> children. A parent type can have multiple child types.

null_char: char

Null literal character (v2.0+). Default: ‘~’.

quote_char: char

Quote character (v2.0+). Default: ‘“’.

count_totals: BTreeMap<String, usize>

Count hints: Type.total -> count (v2.0+).

count_fields: BTreeMap<String, BTreeMap<String, usize>>

Count hints: Type.field:value -> count (v2.0+).

Implementations

impl HeaderInfo

pub fn new() -> Self

Create a new empty header.

pub fn get_schema(&self, type_name: &str) -> Option<&Vec<String>>

Get schema columns for a type.

pub fn get_child_types(&self, parent_type: &str) -> Option<&Vec<String>>

Get child types for a parent type (from NEST).

Trait Implementations

impl Clone for HeaderInfo

fn clone(&self) -> HeaderInfo

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HeaderInfo

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for HeaderInfo

fn default() -> Self

Returns the “default value” for a type.