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Adds Go composite literals:
T{} empty
T{1, 2} positional
T{X: 1, Y: 2} keyed
[]int{1, 2, 3} slice
[3]int{1, 2, 3} array
map[string]int{"a": 1} map
pkg.Point{1, 2} qualified
[]Point{Point{1,2}, Point{3,4}} nested
AST: (list :composite TYPE-OR-EXPR ELEMS). Each element is an
expression or (list :kv KEY VALUE).
Two parser entry points feed the same AST:
* gp-parse-primary picks up type-prefixed composites by seeing
a literal-type starter ([, map, struct) and parsing a type
first, then optionally a '{' body.
* The postfix loop picks up ident-prefixed composites — after
any base expression, '{' wraps it as a composite literal.
Known limitation flagged in plan: when statement parsing arrives,
the postfix '{' branch will misread `if cond { ... }` as a composite
literal. Standard fix: parser-mode flag suppressing composite-lit
disambiguation in control-flow expression positions. Added to plan.
Elided types in nested composites (`[][]int{{1,2},{3,4}}` with the
inner `{1,2}` typed implicitly) deferred.
parse 114/114, total 243/243.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
533 lines
21 KiB
Plaintext
533 lines
21 KiB
Plaintext
;; lib/go/parse.sx — Go parser. Tokenises via go-tokenize (lib/go/lex.sx),
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;; builds canonical AST nodes per lib/guest/ast.sx, and uses
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;; pratt-op-lookup from lib/guest/pratt.sx for operator-precedence climbing.
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;;
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;; Slices so far:
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;; 1. Primary expressions — literal / identifier → ast-literal / ast-var
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;; 2. Binary operators — Pratt precedence climbing against
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;; go-precedence-table; binary application
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;; emitted as (ast-app (ast-var OP) [LHS RHS]).
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;;
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;; The climbing loop is per-language (see lib/guest/pratt.sx header on why)
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;; but the entry shape and lookup are shared.
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;;
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;; All scanner locals are gp- prefixed: SX host primitives silently shadow
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;; guest-language defines.
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(define
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go-precedence-table
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(list
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(list "*" 5 :left)
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(list "/" 5 :left)
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(list "%" 5 :left)
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(list "<<" 5 :left)
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(list ">>" 5 :left)
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(list "&" 5 :left)
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(list "&^" 5 :left)
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(list "+" 4 :left)
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(list "-" 4 :left)
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(list "|" 4 :left)
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(list "^" 4 :left)
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(list "==" 3 :left)
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(list "!=" 3 :left)
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(list "<" 3 :left)
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(list "<=" 3 :left)
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(list ">" 3 :left)
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(list ">=" 3 :left)
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(list "&&" 2 :left)
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(list "||" 1 :left)))
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(define
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go-parse
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(fn
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(src)
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(let
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((gp-tokens (go-tokenize src)) (gp-idx 0))
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(define gp-cur (fn () (nth gp-tokens gp-idx)))
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(define gp-advance! (fn () (set! gp-idx (+ gp-idx 1))))
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(define gp-tok-type (fn () (get (gp-cur) :type)))
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(define gp-tok-value (fn () (get (gp-cur) :value)))
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(define
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gp-parse-primary
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(fn
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()
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(let
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((ty (gp-tok-type)) (v (gp-tok-value)))
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(cond
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(or
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(= ty "int")
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(= ty "float")
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(= ty "imag")
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(= ty "string")
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(= ty "rune"))
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(do (gp-advance!) (ast-literal v))
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(= ty "ident")
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(do (gp-advance!) (ast-var v))
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;; Type-prefixed composite literal starters: [, map, struct.
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;; We parse a full type, then if '{' follows it's a composite
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;; literal; otherwise the type is the operand (the caller
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;; decides what to do — currently statement parsing isn't here).
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(or (and (= ty "op") (= v "["))
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(and (= ty "keyword")
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(or (= v "map") (= v "struct"))))
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(let ((tytree (gp-parse-type)))
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "{"))
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(do
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(gp-advance!)
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(list :composite tytree (gp-parse-composite-elems)))
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:else tytree))
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:else nil))))
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(define
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gp-parse-composite-elems
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;; Caller has consumed '{'. Parses elements until '}'.
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;; Each element: either an expression, or KEY ':' VALUE.
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;; KEY can be an ident (struct field name) or an expression
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;; (map key) — parser is permissive, types phase disambiguates.
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;; Returns a list of expression nodes or (list :kv KEY VALUE).
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(fn
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()
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(let ((elems (list)))
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(define
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gp-comp-loop
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(fn
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()
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(cond
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(= (gp-tok-type) "semi")
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(do (gp-advance!) (gp-comp-loop))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "}"))
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(gp-advance!)
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:else
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(do
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(let ((first (gp-parse-expr 1)))
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(cond
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(and (= (gp-tok-type) "op")
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(= (gp-tok-value) ":"))
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(do
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(gp-advance!)
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(let ((val (gp-parse-expr 1)))
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(append! elems (list :kv first val))))
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:else
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(append! elems first)))
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(when (and (= (gp-tok-type) "op")
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(= (gp-tok-value) ","))
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(gp-advance!))
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(gp-comp-loop)))))
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(gp-comp-loop)
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elems)))
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(define
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gp-parse-call-args
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;; Parse comma-separated args inside (...). Caller has already
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;; consumed the opening "(". Consumes the closing ")".
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;; Returns a list of argument AST nodes.
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(fn
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()
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(let ((args (list)))
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ")"))
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(do (gp-advance!) args)
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:else
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(do
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(let ((first (gp-parse-expr 1)))
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(when (not (= first nil)) (append! args first)))
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(define
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gp-args-rest
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(fn
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()
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ","))
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(do
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(gp-advance!)
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(let ((arg (gp-parse-expr 1)))
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(when (not (= arg nil)) (append! args arg)))
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(gp-args-rest))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ")"))
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(gp-advance!)
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:else nil)))
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(gp-args-rest)
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args)))))
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(define
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gp-parse-interface-elems
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;; Caller positioned BEFORE '{'. Parses elements until '}'.
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;; Two element shapes:
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;; M(params) [results] → (list :method "M" PARAMS RESULTS)
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;; T or pkg.T → (list :embed TYPE)
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;; Type sets (Go 1.18+: ~int | ~float64) deferred.
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(fn
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()
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "{"))
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(gp-advance!))
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(let ((elems (list)))
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(define
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gp-iface-loop
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(fn
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()
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(cond
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(= (gp-tok-type) "semi")
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(do (gp-advance!) (gp-iface-loop))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "}"))
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(gp-advance!)
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(= (gp-tok-type) "ident")
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(do
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(let ((name (gp-tok-value)))
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(gp-advance!)
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(cond
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(and (= (gp-tok-type) "op")
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(= (gp-tok-value) "("))
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(let ((params (gp-parse-func-type-params)))
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(let ((results (gp-parse-func-type-results)))
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(append! elems
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(list :method name params results))))
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(and (= (gp-tok-type) "op")
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(= (gp-tok-value) "."))
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(do
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(gp-advance!)
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(cond
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(= (gp-tok-type) "ident")
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(let ((sel-name (gp-tok-value)))
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(gp-advance!)
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(append! elems
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(list :embed
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(list :ty-sel name sel-name))))
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:else
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(append! elems
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(list :embed (list :ty-name name)))))
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:else
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(append! elems (list :embed (list :ty-name name)))))
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(gp-iface-loop))
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:else nil)))
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(gp-iface-loop)
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elems)))
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(define
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gp-parse-struct-fields
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;; Caller positioned BEFORE '{'. Parses fields until '}'.
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;; field := name [, name]* TYPE
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;; Tolerates ASI-inserted semis between fields. Embedded fields
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;; (anonymous type without preceding names) and field tags are
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;; deferred. Returns a list of (list :field NAMES TYPE).
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(fn
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()
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "{"))
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(gp-advance!))
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(let ((fields (list)))
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(define
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gp-struct-loop
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(fn
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()
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(cond
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(= (gp-tok-type) "semi")
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(do (gp-advance!) (gp-struct-loop))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "}"))
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(gp-advance!)
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(= (gp-tok-type) "ident")
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(do
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(let ((names (list (gp-tok-value))))
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(gp-advance!)
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(define
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gp-names-rest
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(fn
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()
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(when (and (= (gp-tok-type) "op")
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(= (gp-tok-value) ","))
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(gp-advance!)
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(when (= (gp-tok-type) "ident")
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(append! names (gp-tok-value))
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(gp-advance!))
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(gp-names-rest))))
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(gp-names-rest)
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(let ((ty (gp-parse-type)))
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(append! fields (list :field names ty))))
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(gp-struct-loop))
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:else nil)))
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(gp-struct-loop)
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fields)))
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(define
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gp-parse-func-type-params
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;; Anonymous-only func-type params: caller is positioned BEFORE
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;; the opening "(". Returns a list of type AST nodes.
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;; Named params (a int, b string) are deferred — they're needed
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;; for func DECLARATIONS, not pure func-type expressions.
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(fn
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()
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(let ((params (list)))
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "("))
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(gp-advance!))
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ")"))
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(do (gp-advance!) params)
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:else
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(do
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(let ((first (gp-parse-type)))
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(when (not (= first nil)) (append! params first)))
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(define
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gp-params-rest
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(fn
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()
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ","))
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(do
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(gp-advance!)
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(let ((t (gp-parse-type)))
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(when (not (= t nil)) (append! params t)))
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(gp-params-rest))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ")"))
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(gp-advance!)
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:else nil)))
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(gp-params-rest)
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params)))))
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(define
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gp-parse-func-type-results
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;; Zero, one, or many return types. Caller is positioned after
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;; the closing ')' of params.
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;; no return — next token is not a type-starter
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;; single return — bare type follows
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;; multi return — '(' T, T, ... ')'
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(fn
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()
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "("))
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(gp-parse-func-type-params)
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:else
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(let ((t (gp-parse-type)))
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(cond
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(= t nil) (list)
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:else (list t))))))
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(define
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gp-parse-type
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;; Go type-expression parser. Covers:
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;; *T → (list :ty-ptr T)
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;; name → (list :ty-name "name")
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;; pkg.Name → (list :ty-sel "pkg" "Name")
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;; []T → (list :ty-slice T)
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;; [N]T → (list :ty-array N T)
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;; map[K]V → (list :ty-map K V)
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;; chan T → (list :ty-chan :both T)
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;; chan<- T → (list :ty-chan :send T)
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;; <-chan T → (list :ty-chan :recv T)
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;; Struct, interface, func types are deferred to a later slice.
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(fn
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()
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "*"))
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(do (gp-advance!) (list :ty-ptr (gp-parse-type)))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "["))
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(do
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(gp-advance!)
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "]"))
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(do (gp-advance!) (list :ty-slice (gp-parse-type)))
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:else
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(let ((sz (gp-parse-expr 1)))
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "]"))
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(gp-advance!))
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(list :ty-array sz (gp-parse-type)))))
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(and (= (gp-tok-type) "keyword") (= (gp-tok-value) "map"))
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(do
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(gp-advance!)
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "["))
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(gp-advance!))
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(let ((k (gp-parse-type)))
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(when (and (= (gp-tok-type) "op") (= (gp-tok-value) "]"))
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(gp-advance!))
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(let ((v (gp-parse-type)))
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(list :ty-map k v))))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "<-"))
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(do
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(gp-advance!)
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(when (and (= (gp-tok-type) "keyword") (= (gp-tok-value) "chan"))
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(gp-advance!))
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(list :ty-chan :recv (gp-parse-type)))
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(and (= (gp-tok-type) "keyword") (= (gp-tok-value) "chan"))
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(do
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(gp-advance!)
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "<-"))
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(do (gp-advance!) (list :ty-chan :send (gp-parse-type)))
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:else (list :ty-chan :both (gp-parse-type))))
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(and (= (gp-tok-type) "keyword") (= (gp-tok-value) "func"))
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(do
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(gp-advance!)
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(let ((params (gp-parse-func-type-params)))
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(let ((results (gp-parse-func-type-results)))
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(list :ty-func params results))))
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(and (= (gp-tok-type) "keyword") (= (gp-tok-value) "struct"))
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(do
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(gp-advance!)
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(list :ty-struct (gp-parse-struct-fields)))
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(and (= (gp-tok-type) "keyword") (= (gp-tok-value) "interface"))
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(do
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(gp-advance!)
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(list :ty-interface (gp-parse-interface-elems)))
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(= (gp-tok-type) "ident")
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(let ((name (gp-tok-value)))
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(gp-advance!)
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "."))
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(do
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(gp-advance!)
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(cond
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(= (gp-tok-type) "ident")
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(let ((sel-name (gp-tok-value)))
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(gp-advance!)
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(list :ty-sel name sel-name))
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:else (list :ty-name name)))
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:else (list :ty-name name)))
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:else nil)))
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(define
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gp-parse-bracket-expr
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;; Optional expression inside brackets — returns nil if next token
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;; is ':' or ']' (the slice "omitted" cases).
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(fn
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()
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(cond
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(and (= (gp-tok-type) "op")
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(or (= (gp-tok-value) ":") (= (gp-tok-value) "]")))
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nil
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:else (gp-parse-expr 1))))
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(define
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gp-parse-bracket
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;; Caller has consumed '['. Parses index or slice and ']'.
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;; x[i] → (list :index BASE i)
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;; x[a:b] → (list :slice BASE LOW HIGH nil) (LOW/HIGH may be nil)
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;; x[a:b:c] → (list :slice BASE LOW HIGH MAX)
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;; Returns the AST node based on BASE.
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(fn
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(base)
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(let ((low (gp-parse-bracket-expr)))
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "]"))
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(do (gp-advance!) (list :index base low))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ":"))
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(do
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(gp-advance!)
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(let ((high (gp-parse-bracket-expr)))
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(cond
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(and (= (gp-tok-type) "op") (= (gp-tok-value) "]"))
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(do (gp-advance!) (list :slice base low high nil))
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(and (= (gp-tok-type) "op") (= (gp-tok-value) ":"))
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(do
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(gp-advance!)
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(let ((maxe (gp-parse-bracket-expr)))
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(when (and (= (gp-tok-type) "op")
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(= (gp-tok-value) "]"))
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(gp-advance!))
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(list :slice base low high maxe)))
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:else (list :slice base low high nil))))
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:else base))))
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(define
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gp-parse-postfix
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;; Left-associative postfix loop on top of gp-parse-primary:
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;; x.field → (list :select x "field") — Go-specific
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;; f(args...) → (ast-app f args) — canonical
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;; x[i] → (list :index x i) — Go-specific
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;; x[a:b] → (list :slice x low high max) — Go-specific
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(fn
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()
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(let ((base (gp-parse-primary)))
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(gp-postfix-loop base))))
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(define
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gp-postfix-loop
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(fn
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(base)
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(cond
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(= base nil) nil
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:else
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(let ((tok (gp-cur)))
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(cond
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(and (= (get tok :type) "op") (= (get tok :value) "."))
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(do
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(gp-advance!)
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(let ((next-tok (gp-cur)))
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(cond
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;; .(T) — type assertion
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(and (= (get next-tok :type) "op")
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(= (get next-tok :value) "("))
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(do
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(gp-advance!)
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(let ((ty (gp-parse-type)))
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(when (and (= (gp-tok-type) "op")
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(= (gp-tok-value) ")"))
|
|
(gp-advance!))
|
|
(gp-postfix-loop (list :assert base ty))))
|
|
;; .ident — selector / member access
|
|
(= (get next-tok :type) "ident")
|
|
(do
|
|
(gp-advance!)
|
|
(gp-postfix-loop
|
|
(list :select base (get next-tok :value))))
|
|
:else base)))
|
|
(and (= (get tok :type) "op") (= (get tok :value) "("))
|
|
(do
|
|
(gp-advance!)
|
|
(gp-postfix-loop (ast-app base (gp-parse-call-args))))
|
|
(and (= (get tok :type) "op") (= (get tok :value) "["))
|
|
(do
|
|
(gp-advance!)
|
|
(gp-postfix-loop (gp-parse-bracket base)))
|
|
;; Ident-prefixed composite literal: T{...}. The base is
|
|
;; the AST expression for the type-name (an ast-var or a
|
|
;; :select node); a later phase resolves it as a type.
|
|
(and (= (get tok :type) "op") (= (get tok :value) "{"))
|
|
(do
|
|
(gp-advance!)
|
|
(gp-postfix-loop
|
|
(list :composite base (gp-parse-composite-elems))))
|
|
:else base)))))
|
|
(define
|
|
gp-unary-ops
|
|
;; Go spec § Operators: prefix unary, all higher precedence than
|
|
;; any binary operator. <- is the channel receive form (send is a
|
|
;; statement, not an expression, so never appears here as binary).
|
|
(list "+" "-" "!" "^" "*" "&" "<-"))
|
|
(define
|
|
gp-parse-unary
|
|
(fn
|
|
()
|
|
(let ((tok (gp-cur)))
|
|
(cond
|
|
(and (= (get tok :type) "op")
|
|
(some (fn (u) (= u (get tok :value))) gp-unary-ops))
|
|
(do
|
|
(gp-advance!)
|
|
(let ((operand (gp-parse-unary)))
|
|
(cond
|
|
(= operand nil) nil
|
|
:else (ast-app (ast-var (get tok :value)) (list operand)))))
|
|
:else (gp-parse-postfix)))))
|
|
(define
|
|
gp-parse-expr
|
|
(fn
|
|
(min-prec)
|
|
(let ((left (gp-parse-unary))) (gp-pratt-loop left min-prec))))
|
|
(define
|
|
gp-pratt-loop
|
|
(fn
|
|
(left min-prec)
|
|
(cond
|
|
(= left nil) nil
|
|
:else
|
|
(let
|
|
((tok (gp-cur)))
|
|
(cond
|
|
(not (= (get tok :type) "op"))
|
|
left
|
|
:else (let
|
|
((entry (pratt-op-lookup go-precedence-table (get tok :value))))
|
|
(cond
|
|
(= entry nil)
|
|
left
|
|
(< (pratt-op-prec entry) min-prec)
|
|
left
|
|
:else (do
|
|
(gp-advance!)
|
|
(let
|
|
((next-min (if (= (pratt-op-assoc entry) :left) (+ (pratt-op-prec entry) 1) (pratt-op-prec entry))))
|
|
(let
|
|
((right (gp-parse-expr next-min)))
|
|
(gp-pratt-loop
|
|
(ast-app
|
|
(ast-var (get tok :value))
|
|
(list left right))
|
|
min-prec)))))))))))
|
|
(gp-parse-expr 1))))
|