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Parser

Parse-literal

Attempts to eat a literal and build a literal AST node.

Signature
(parse-literal tokens) → (mv ast-node tokens-after-literal-or-reserr)
Arguments: tokens — Guard (abnf::tree-listp tokens).
Returns: ast-node — Type (literal-optionp ast-node).; tokens-after-literal-or-reserr — Type (abnf::tree-list-resultp tokens-after-literal-or-reserr).

Returns two values: an optional literal AST node and either the list of remaining tokens or a reserr.

If a valid literal token is found, the first value returned is a literal AST node of the appropriate kind. Different kinds have different substructure.

If no literal is found, the first value returned is NIL and the second value is a reserr.

Definitions and Theorems

Function: parse-literal

(defun parse-literal (tokens)
 (declare (xargs :guard (abnf::tree-listp tokens)))
 (let ((__function__ 'parse-literal))
  (declare (ignorable __function__))
  (b*
   (((when (endp tokens))
     (mv nil
         (reserrf
              (cons "ran out of tokens when trying to parse literal"
                    tokens))))
    ((unless (abnf::tree-listp tokens))
     (mv nil (reserrf "guard of parse-literal")))
    (putative-literal-tree (first tokens))
    ((unless
      (and
        (abnf::tree-case putative-literal-tree :nonleaf)
        (equal (abnf::tree-nonleaf->rulename? putative-literal-tree)
               (abnf::rulename "literal"))))
     (mv nil
         (reserrf (cons "token is not a literal" tokens))))
    (branches (abnf::tree-nonleaf->branches putative-literal-tree))
    ((unless (and (listp branches)
                  (equal (len branches) 1)
                  (listp (car branches))
                  (equal (len (car branches)) 1)
                  (abnf::treep (caar branches))
                  (abnf::tree-case (caar branches)
                                   :nonleaf)))
     (prog2$
      (er
       hard? 'top-level
       "literal token seems to have the wrong structure for a literal")
      (mv nil
          (reserrf (cons "program logic error 2" tokens)))))
    (parsed-literal-kind (cst2ast-literal-kind (caar branches)))
    ((when (null parsed-literal-kind))
     (mv nil
         (reserrf "problem with literal substructure"))))
   (mv parsed-literal-kind (rest tokens)))))

Theorem: literal-optionp-of-parse-literal.ast-node

(defthm literal-optionp-of-parse-literal.ast-node
  (b* (((mv ?ast-node
            ?tokens-after-literal-or-reserr)
        (parse-literal tokens)))
    (literal-optionp ast-node))
  :rule-classes :rewrite)

Theorem: tree-list-resultp-of-parse-literal.tokens-after-literal-or-reserr

(defthm
  tree-list-resultp-of-parse-literal.tokens-after-literal-or-reserr
  (b* (((mv ?ast-node
            ?tokens-after-literal-or-reserr)
        (parse-literal tokens)))
    (abnf::tree-list-resultp tokens-after-literal-or-reserr))
  :rule-classes :rewrite)

Theorem: len-of-parse-literal-<

(defthm len-of-parse-literal-<
  (b* (((mv ?ast-node
            ?tokens-after-literal-or-reserr)
        (parse-literal tokens)))
    (implies (not (reserrp tokens-after-literal-or-reserr))
             (< (len tokens-after-literal-or-reserr)
                (len tokens))))
  :rule-classes :linear)