ast

Documentation

Overview

Package ast defines the runtime value AST nodes shared across the txcl parser, runtime evaluator, and processor. The package is a leaf — it depends on nothing — so downstream packages (runtime, resonator, processor) can all reference it without creating import cycles when the runtime evaluator (chassis/txcl/runtime) is introduced.

Value is a discriminated sum:

• Literal{V} — a parsed scalar or array literal.
• PathRef{Path} — an `@x.y.z` envelope reference. Reserved for future use; the parser does not produce this node yet (paths on the RHS of SET/EMIT/WITH are not supported in the current grammar).
• FunctionCall{Name,Args} — a `&fn(args...)` runtime call. Reserved; parser does not produce this yet either.

See internal docs/todo-txcl-expressions.md for the broader plan; this package lands the AST shape so the runtime evaluator can be added next without a churn-heavy retrofit.

Index

• func LiteralOrNil(v Value) interface{}
• type FunctionCall
• type Literal
• type PathRef
• type Value

Functions

func LiteralOrNil

func LiteralOrNil(v Value) interface{}

LiteralOrNil extracts the wrapped value from an ast.Literal, returning nil for any other Value type (including a nil Value). Convenience for transitional code that pre-dates the runtime evaluator — every call site that uses this should ultimately migrate to runtime.Resolve, which handles all three node types.

Types

type FunctionCall

type FunctionCall struct {
	Name string
	Args []Value
}

FunctionCall is a `&fn(args...)` runtime call. Resolved by the runtime evaluator through the function registry. Args may include nested FunctionCall nodes (resolution is recursive).

type Literal

type Literal struct {
	V interface{}
}

Literal wraps a parsed scalar (string, int64, float64, bool) or array literal ([]interface{}). The underlying type is whatever the parser produced — this struct only carries it, it does not constrain it.

type PathRef

type PathRef struct {
	Path string
}

PathRef is an envelope path reference (`@x.y.z`). Resolved by the runtime evaluator against the current envelope.

type Value

type Value interface {
	// contains filtered or unexported methods
}

Value is one node in the value-expression tree. The closed set of implementations is Literal, PathRef, and FunctionCall.