ast

type AliasDecl ¶

type AliasDecl struct {
	DeclHead
	Params []*TypeParam
	Target *TypeRef
}

AliasDecl is an `alias Name = TypeRef` declaration, optionally parameterized. An alias is transparent: it is expanded rather than referenced.

type AssocTypeBind ¶

type AssocTypeBind struct {
	P      Position
	N      string
	Target *TypeRef
}

AssocTypeBind supplies a type for one of a class's associated type requirements.

type AssocTypeReq ¶

type AssocTypeReq struct {
	Doc  []string
	P    Position
	N    string
	Kind *Kind
}

AssocTypeReq is a `type Cursor` requirement: an implementor supplies a type, and an instance binds it.

func (a *AssocTypeReq) MemberPos() Position

type ClassDecl ¶

type ClassDecl struct {
	DeclHead
	Params   []*TypeParam
	FunDeps  []*FunDep
	Conforms []*ClassRef // classes this one requires
	Requires []*ClassRef
	Members  []Member
	End      Position // the body's `}`
}

ClassDecl is a contract. It declares nothing into the types that satisfy it; conformance is nominal and always declared.

type ClassRef ¶

type ClassRef struct {
	P         Position
	Qualifier string
	N         string
	Args      []*TypeArg
}

ClassRef names a class, optionally qualified and applied to arguments. It is syntactically a named type reference, but the two are different kinds of thing and the tree keeps them apart.

type Comment ¶ added in v0.1.7

type Comment struct {
	P    Position
	Text string // the text after the slashes, with one leading space removed
}

Comment is one ordinary `//` comment.

type Constraint ¶

type Constraint struct {
	P    Position
	N    string
	Args []*Literal
}

Constraint is one entry in a `where { ... }` block.

The set of names is open. The compiler checks the arity and argument kinds of the standard names and passes everything else through, so a backend may understand a constraint the compiler has never heard of.

type Decl ¶

type Decl interface {
	Pos() Position
	Name() string
	// contains filtered or unexported methods
}

Decl is a top-level declaration. `class` and `instance` arrive with phase 4 of docs/design/parser-plan.md; every other form is here.

type DeclHead ¶

type DeclHead struct {
	Doc []string
	P   Position
	N   string
	Dep *Deprecation
}

DeclHead is the part every declaration shares: its doc comment, its position, its name, and whether it is deprecated.

func (h *DeclHead) Name() string

func (h *DeclHead) Pos() Position

type Deprecation ¶

type Deprecation struct {
	P      Position
	Reason string // "" when written without a reason
}

Deprecation marks a declaration, field, or variant as on its way out.

func Deprecated(d Decl) *Deprecation

type Directive ¶

type Directive struct {
	P    Position
	N    string
	Args []*Literal
}

Directive is an opaque instruction to a backend. The compiler checks its shape and hands it over; what it means is the backend's business.

type EnumDecl ¶

type EnumDecl struct {
	DeclHead
	Params   []*TypeParam
	Conforms []*ClassRef
	Requires []*ClassRef
	Variants []*Variant
	End      Position // the body's `}`
}

EnumDecl is a closed set of variants. A variant may carry fields, which makes enum the language's sum type.

type Field ¶

type Field struct {
	Doc         []string
	P           Position
	N           string
	Key         bool // part of the entity's identity
	Owned       bool // composition rather than reference
	Dep         *Deprecation
	Type        *TypeRef
	Constraints []*Constraint
	Default     *Literal
	End         Position // the constraint block's `}`; zero without one
}

Field is a named, typed member.

func (f *Field) MemberPos() Position

type File ¶

type File struct {
	Filename string
	Package  *PackageDecl // nil if omitted
	Imports  []*ImportDecl
	Decls    []Decl

	// Comments holds every ordinary `//` comment in the file, in source
	// order. They are not attached to any node: a comment can sit
	// anywhere, so the formatter places each one by position rather than
	// the tree carrying it. Doc comments are not here; those belong to the
	// declaration they precede and live in its Doc.
	Comments []*Comment

	// End is the position of the end of the file, which is what a comment
	// after the last declaration is placed against.
	End Position
}

File is a single parsed .tdl source file.

type FunDep ¶

type FunDep struct {
	P    Position
	From []string
	To   []string
}

FunDep states that some parameters determine others, which makes a multi-parameter class a function rather than a table.

type ImportDecl ¶

type ImportDecl struct {
	Doc   []string
	P     Position
	Path  string
	Alias string // "_" merges the imported names into the current scope
}

ImportDecl is an `import "path.tdl" as alias` declaration.

type Include ¶

type Include struct {
	P    Position
	Type *ClassRef
}

Include copies a mixin's fields into the including declaration.

func (i *Include) MemberPos() Position

type InstanceDecl ¶

type InstanceDecl struct {
	DeclHead // N is the class name
	Params   []*TypeParam
	Class    *ClassRef
	For      *TypeRef // set when written with `for`, nil when written with type arguments
	Requires []*ClassRef
	Binds    []*AssocTypeBind
	End      Position // the bind block's `}`; zero without one
}

InstanceDecl declares that a type satisfies a class.

`instance C for T` is sugar for `instance C<T>`, available when the class takes one parameter. The parser records which was written.

type KeyRequirement ¶

type KeyRequirement struct {
	P Position
}

KeyRequirement is a bare `key` in a class body: an implementor must have some key, without the class saying which.

func (k *KeyRequirement) MemberPos() Position

type Kind ¶

type Kind struct {
	P     Position
	N     string // "type" or "unit"; empty when Paren is set
	Paren *Kind
	Arrow *Kind // `left -> Arrow`; nil for a bare atom
}

Kind is a kind expression. Name is "type" or "unit" for an atom, or Paren holds a parenthesized kind; Arrow is set when this kind is the left side of an arrow, which associates to the right.

type Literal ¶

type Literal struct {
	P     Position
	Kind  LiteralKind
	Text  string     // decoded for LitString, pattern body for LitRegex, source text otherwise
	Items []*Literal // set for LitList
	Lo    *Literal   // set for LitRange; nil when the range is open below
	Hi    *Literal   // set for LitRange; nil when the range is open above
}

Literal is a literal value: a field default, a constraint argument, or a directive argument.

type LiteralKind ¶

type LiteralKind int

LiteralKind identifies which form a Literal takes.

const (
	LitString LiteralKind = iota
	LitInt
	LitFloat
	LitBool
	LitList
	LitName  // a dotted name, denoting an enum variant
	LitRegex // /.../, a constraint argument
	LitRange // 3..254, 1.., ..254
)

type Member ¶

type Member interface {
	MemberPos() Position
}

Member is one item in a StructDecl body: a Field or an Include.

type NewtypeDecl ¶

type NewtypeDecl struct {
	DeclHead
	Params      []*TypeParam
	Base        *TypeRef
	Requires    []*ClassRef
	Constraints []*Constraint
	End         Position // the constraint block's `}`; zero without one
}

NewtypeDecl is a `type Name: Base` declaration. A newtype is distinct from the type it is built on.

type PackageDecl ¶

type PackageDecl struct {
	P    Position
	Path string // dotted, e.g. "shop.orders"
}

PackageDecl is a `package <dotted.ident>` declaration.

type Position ¶

type Position = lex.Position

Position identifies a location in a source file.

type PrimitiveDecl ¶

type PrimitiveDecl struct {
	DeclHead
	Kind *Kind // nil when the kind is left to inference
}

PrimitiveDecl is a `primitive Name` or `primitive Name: Kind` declaration. It introduces an opaque, irreducible root type.

type StructDecl ¶

type StructDecl struct {
	DeclHead
	Keyword  string // "entity", "value", or "mixin"
	Params   []*TypeParam
	Conforms []*ClassRef
	Requires []*ClassRef
	Members  []Member
	End      Position // the body's `}`
}

StructDecl is a declaration with a body of members: `entity`, `value`, or `mixin`. The three share a shape and differ in meaning, so the keyword is recorded rather than split across three identical node types.

type TargetDecl ¶

type TargetDecl struct {
	DeclHead
	For     string // the dotted package name the target applies to
	Entries []*TargetEntry
	End     Position // the block's `}`
}

TargetDecl is a `target go for billing { ... }` block. Everything a code generator needs lives here rather than in the model.

type TargetEntry ¶

type TargetEntry struct {
	P         Position
	Path      string         // "" for a bare directive
	Directive *Directive     // nil when Entries is set
	Entries   []*TargetEntry // nil when Directive is set
	End       Position       // the nested block's `}`; zero without one
}

TargetEntry is one entry in a TargetDecl: a path scoping a nested block, a path mapped to a directive, or a bare directive applying to the enclosing scope.

type TypeArg ¶

type TypeArg struct {
	P    Position
	Type *TypeRef  // set unless Unit is
	Unit *UnitExpr // set only when operators made the argument unambiguous
}

TypeArg is one argument in a `<...>` list. It is a type or a unit, and the two are told apart by kind rather than by syntax: a bare name could be either, so the parser records what was written and the resolver decides against the declaration being applied.

type TypeParam ¶

type TypeParam struct {
	P    Position
	N    string
	Kind *Kind // nil when inferred from use
}

TypeParam is one parameter in a `<...>` parameter list, with an optional kind annotation.

type TypeRef ¶

type TypeRef struct {
	P Position

	// Named form: an optionally qualified name with optional arguments.
	Qualifier string // "" if unqualified; set for "alias.Type"
	N         string // "" for the collection forms below
	Args      []*TypeArg

	List *TypeRef // [T]
	Set  *TypeRef // {T}

	MapKey   *TypeRef // {K -> V}
	MapValue *TypeRef

	Optional bool // trailing ?
	Nullable bool // trailing | null
}

TypeRef is a reference to a type.

The collection and optionality forms are sugar for prelude types, and the parser records the form as written: lowering to List, Set, Map, Option, and Nullable is the resolver's job.

type UnitDecl ¶

type UnitDecl struct {
	DeclHead
	Expr *UnitExpr // nil for a base unit
}

UnitDecl is a `unit kg` or `unit N = kg*m/s^2` declaration. A unit without an expression is a base unit; one with an expression is derived and reduces to base dimensions before comparison.

type UnitExpr ¶

type UnitExpr struct {
	P     Position
	Terms []*UnitTerm
}

UnitExpr is a product and quotient of unit terms.

type UnitTerm ¶

type UnitTerm struct {
	P     Position
	Op    string    // "" for the first term, otherwise "*" or "/"
	N     string    // unit name; "" when Paren is set
	Exp   int       // exponent; 1 when written without one
	Paren *UnitExpr // set for a parenthesized sub-expression
}

UnitTerm is one factor of a UnitExpr.

type Variant ¶

type Variant struct {
	Doc    []string
	P      Position
	N      string
	Dep    *Deprecation
	Fields []*Field // nil for a variant without a payload
	End    Position // the payload's `}`; zero without one
}

Variant is one alternative in an EnumDecl.