Struct passerine::compiler::rule::Rule

pub struct Rule {
    pub arg_pat: Spanned<ArgPattern>,
    pub tree: Spanned<AST>,
}

A rule has an Argument Pattern and an AST. When a form matches the ArgPattern, a set of bindings are produced, which are then spliced into the Rule’s AST to make a new AST. This is done in a hygenic manner.

Fields

arg_pat: Spanned<ArgPattern>

tree: Spanned<AST>

Implementations

impl Rule

pub fn new(
    arg_pat: Spanned<ArgPattern>,
    tree: Spanned<AST>
) -> Result<Rule, Syntax>

Builds a new rule, making sure the rule’s signature is valid.

pub fn keywords(arg_pat: &Spanned<ArgPattern>) -> Vec<String>

Returns all keywords, as strings, used by the macro, in order of usage. Does not filter for duplicates.

pub fn merge_safe(
    base: &mut HashMap<String, Spanned<AST>>,
    new: HashMap<String, Spanned<AST>>,
    def: Span
) -> Result<(), Syntax>

Merges two maps of bindings. If there is a collision, i.e. a name bound in both bindings, An error highlighting the duplicate binding is returned.

pub fn bind(
    arg_pat: &Spanned<ArgPattern>,
    reversed_form: &mut Vec<Spanned<AST>>
) -> Option<Result<HashMap<String, Spanned<AST>>, Syntax>>

Traverses a form, creating bindings for subsequent transformation. Returns None if the form does not match the argument pattern. Some(Ok(_)) if it matches successfully, and Some(Err(_)) if it matches but something is incorrect. You must check that the passed &mut reversed_form is empty to gaurantee the match occured in full Note that this function takes the form unwrapped and in reverse - This is to make processing the bindings more efficient, As this function works with the head of the form.

pub fn remove_tag(base: &str) -> String

Turns a tagged random identifier, like <base>#XXXXXXXX back into <base>. If the identifier is not tagged, this function just returns <base>.

pub fn unique_tag(
    base: String,
    bindings: &HashMap<String, Spanned<AST>>
) -> String

Turns a base identifier into a random identifier of the format <base>#XXXXXXXX, Gauranteed not to exist in bindings.

pub fn resolve_symbol(
    name: String,
    span: Span,
    bindings: &mut HashMap<String, Spanned<AST>>
) -> Spanned<AST>

Resolves a symbol. If the symbol has been bound, i.e. is defined in the Argument CSTPattern, we simply splice that in. If not, we hygenically replace it with a unique variable.

pub fn expand_pattern(
    pattern: Spanned<ASTPattern>,
    bindings: &mut HashMap<String, Spanned<AST>>
) -> Result<Spanned<ASTPattern>, Syntax>

Expands the bindings in a pattern.

pub fn expand_arg_pat(
    arg_pat: Spanned<ArgPattern>,
    bindings: &mut HashMap<String, Spanned<AST>>
) -> Result<Spanned<ArgPattern>, Syntax>

~Macros inside of macros is a bit too meta for me to think about atm.~ No longer! A macro inside a macro is a macro completely local to that macro. The argument patterns inside a macro can be extended.

pub fn expand(
    tree: Spanned<AST>,
    bindings: &mut HashMap<String, Spanned<AST>>
) -> Result<Spanned<AST>, Syntax>

Takes a macro’s tree and a set of bindings and produces a new hygenic tree.

Trait Implementations

impl Clone for Rule

fn clone(&self) -> Rule

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Rule

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

Formats the value using the given formatter.