Commit 59e07d92 authored by POTTIER Francois's avatar POTTIER Francois

Documented the incremental interface, i.e. [start] and [offer],

in [EngineTypes].
parent d30bc806
......@@ -283,6 +283,10 @@ module type ENGINE = sig
type semantic_value
(* ------------------------------------------------------------------------- *)
(* The monolithic interface, where the parser controls the lexer. *)
(* An entry point to the engine requires a start state, a lexer, and a lexing
buffer. It either succeeds and produces a semantic value, or fails and
raises [Error]. *)
......@@ -295,4 +299,47 @@ module type ENGINE = sig
Lexing.lexbuf ->
semantic_value
(* ------------------------------------------------------------------------- *)
(* The incremental interface, where the user controls the lexer and the
parser suspends itself when it needs to read a new token. *)
(* The type [result] represents an intermediate or final result of the
parser. An intermediate result can be thought of as a suspension: it
records the parser's current state, and allows parsing to be resumed.
[InputNeeded] is an intermediate result, and means that the parser
wishes to read one token before continuing. [Accepted] and [Rejected]
are final results. *)
type env
type result = private
| InputNeeded of env
| Accepted of semantic_value
| Rejected
(* [start] is an entry point. It requires just a start state, and begins
the parsing process. It produces a result, which usually will be an
[InputNeeded] result. (It could be [Accepted] if this starting state
accepts only the empty word. It could be [Rejected] if this starting
state accepts no word at all.) It does not raise any exception. *)
val start:
state ->
result
(* [offer] allows the user to resume the parser after it has suspended
itself with an [InputNeeded] result. [offer] expects this result, as
well as a new token, and produces a new result. It does not raise any
exception. *)
val offer:
result ->
token * Lexing.position * Lexing.position ->
result
(* The incremental interface is more general than the monolithic one.
[entry] can be (and is indeed) implemented by first calling [start],
then calling [offer] in a loop, until a final result is obtained. *)
end
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