Struct HostApi 

#[repr(C)]
pub struct HostApi {

    pub abi_version: u32,
    pub ctx: *mut c_void,
    pub register_builtin: extern "C" fn(host: *const HostApi, name: *const c_char, handler: BuiltinFn) -> c_int,
    pub print: extern "C" fn(host: *const HostApi, text: *const c_char),
    pub eval: extern "C" fn(host: *const HostApi, code: *const c_char) -> c_int,
    pub getvar: extern "C" fn(host: *const HostApi, name: *const c_char) -> *mut c_char,
    pub setvar: extern "C" fn(host: *const HostApi, name: *const c_char, value: *const c_char) -> c_int,
    pub free_cstring: extern "C" fn(host: *const HostApi, s: *mut c_char),
    pub register_completion: extern "C" fn(host: *const HostApi, cmd: *const c_char, generator: *const c_char) -> c_int,
    pub getfunction: extern "C" fn(host: *const HostApi, name: *const c_char) -> *mut c_char,
    pub addfunction: extern "C" fn(host: *const HostApi, name: *const c_char, body: *const c_char) -> c_int,
    pub register_compfn: extern "C" fn(host: *const HostApi, name: *const c_char, handler: CompFn) -> c_int,
    pub comp_dispatch: extern "C" fn(host: *const HostApi, name: *const c_char, argc: usize, argv: *const *const c_char) -> c_int,
    pub empty_command_hash: extern "C" fn(host: *const HostApi),
}

The host API table handed to the plugin. Every field is a C-ABI function pointer into zshrs. Layout is frozen by ABI_VERSION.

A single instance lives for the whole process; plugins may store the *const HostApi they are given and call through it from any builtin.

Fields

abi_version: u32

Must equal ABI_VERSION. Checked by the plugin’s own declare_plugin! glue before it trusts the rest of the table.

ctx: *mut c_void

Reserved for the host; opaque to plugins. Currently null.

register_builtin: extern "C" fn(host: *const HostApi, name: *const c_char, handler: BuiltinFn) -> c_int

Register a command name → handler. Returns 0 on success. Names registered here resolve as commands in the shell (after real builtins, before PATH lookup). name is copied by the host.

print: extern "C" fn(host: *const HostApi, text: *const c_char)

Write text to the shell’s stdout (no trailing newline added).

eval: extern "C" fn(host: *const HostApi, code: *const c_char) -> c_int

Evaluate a fragment of shell code in the host and return its exit status. code is UTF-8, NUL-terminated.

getvar: extern "C" fn(host: *const HostApi, name: *const c_char) -> *mut c_char

Read a shell scalar parameter by name. Returns a freshly allocated C string the caller MUST release with free_cstring, or null if the parameter is unset.

setvar: extern "C" fn(host: *const HostApi, name: *const c_char, value: *const c_char) -> c_int

Set a shell scalar parameter. Returns 0 on success.

free_cstring: extern "C" fn(host: *const HostApi, s: *mut c_char)

Release a string previously returned by getvar.

register_completion: extern "C" fn(host: *const HostApi, cmd: *const c_char, generator: *const c_char) -> c_int

Register a native completion for command cmd. generator names a builtin that prints one candidate per line for the current word (see Host::add_match). The host wires it into zsh’s completion system (compsys) lazily — the actual compdef runs the first time completion fires, at a safe point in the completion pipeline, so this is cheap and safe to call from znative_init. Returns 0 on success. (ABI v2.)

getfunction: extern "C" fn(host: *const HostApi, name: *const c_char) -> *mut c_char

Read a shell function’s body by name — the same deparsed text ${functions[name]} yields (one statement per line, tab-indented; builtin autoload -X… for an autoload stub). Returns a freshly allocated C string the caller MUST release with free_cstring, or null if no such function is defined. This is the only structured read of a function; getvar reads scalars, eval returns only a status. (ABI v3.)

addfunction: extern "C" fn(host: *const HostApi, name: *const c_char, body: *const c_char) -> c_int

Define (or replace) a shell function name with body — exactly like functions[name]=body: the body is parsed and installed in shfunctab, so a subsequent getfunction returns its deparsed form and the shell can call it (as a command, ZLE widget, hook, …). Returns 0 on success, non-zero if body fails to parse. (ABI v3.)

register_compfn: extern "C" fn(host: *const HostApi, name: *const c_char, handler: CompFn) -> c_int

Register a native override for the compsys function name (a _NAME, e.g. _command_names). Once registered, the host’s completion router dispatches handler in place of the built-in Rust port or the autoloaded shell function. Returns 0 on success. name is copied by the host. (ABI v4.)

comp_dispatch: extern "C" fn(host: *const HostApi, name: *const c_char, argc: usize, argv: *const *const c_char) -> c_int

Invoke a compsys function name (e.g. _alternative, _path_commands) with argv[0..argc] as its arguments — the host resolves it exactly as the completer chain would (native port, then shell autoload), in the current completion scope so local/tag state nests correctly. Returns the function’s status. This is how an overriding CompFn delegates the bulk of its work. (ABI v4.)

empty_command_hash: extern "C" fn(host: *const HostApi)

Empty the shell’s command-name hash (cmdnamtab), the observable effect of local -a +h path; local -A +h commands inside a completion function: a subsequent compadd -k commands then adds nothing until the hash refills. Used by an overriding _command_names to reproduce the customized shadow. (ABI v4.)