.TH "Stdlib.Parsing" 3o 2023-09-18 OCamldoc "OCaml library"
.SH NAME
Stdlib.Parsing \- no description
.SH Module
Module   Stdlib.Parsing
.SH Documentation
.sp
Module
.BI "Parsing"
 : 
.B (module Stdlib__Parsing)

.sp

.sp

.sp
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.I val symbol_start 
: 
.B unit -> int
.sp

.ft B
symbol_start
.ft R
and 
.ft B
Parsing\&.symbol_end
.ft R
are to be called in the
action part of a grammar rule only\&. They return the offset of the
string that matches the left\-hand side of the rule: 
.ft B
symbol_start()
.ft R
returns the offset of the first character; 
.ft B
symbol_end()
.ft R
returns the
offset after the last character\&. The first character in a file is at
offset 0\&.

.sp

.I val symbol_end 
: 
.B unit -> int
.sp
See 
.ft B
Parsing\&.symbol_start
.ft R
\&.

.sp

.I val rhs_start 
: 
.B int -> int
.sp
Same as 
.ft B
Parsing\&.symbol_start
.ft R
and 
.ft B
Parsing\&.symbol_end
.ft R
, but
return the offset of the string matching the 
.ft B
n
.ft R
th item on the
right\-hand side of the rule, where 
.ft B
n
.ft R
is the integer parameter
to 
.ft B
rhs_start
.ft R
and 
.ft B
rhs_end
.ft R
\&. 
.ft B
n
.ft R
is 1 for the leftmost item\&.

.sp

.I val rhs_end 
: 
.B int -> int
.sp
See 
.ft B
Parsing\&.rhs_start
.ft R
\&.

.sp

.I val symbol_start_pos 
: 
.B unit -> Lexing.position
.sp
Same as 
.ft B
symbol_start
.ft R
, but return a 
.ft B
position
.ft R
instead of an offset\&.

.sp

.I val symbol_end_pos 
: 
.B unit -> Lexing.position
.sp
Same as 
.ft B
symbol_end
.ft R
, but return a 
.ft B
position
.ft R
instead of an offset\&.

.sp

.I val rhs_start_pos 
: 
.B int -> Lexing.position
.sp
Same as 
.ft B
rhs_start
.ft R
, but return a 
.ft B
position
.ft R
instead of an offset\&.

.sp

.I val rhs_end_pos 
: 
.B int -> Lexing.position
.sp
Same as 
.ft B
rhs_end
.ft R
, but return a 
.ft B
position
.ft R
instead of an offset\&.

.sp

.I val clear_parser 
: 
.B unit -> unit
.sp
Empty the parser stack\&. Call it just after a parsing function
has returned, to remove all pointers from the parser stack
to structures that were built by semantic actions during parsing\&.
This is optional, but lowers the memory requirements of the
programs\&.

.sp

.I exception Parse_error 

.sp
Raised when a parser encounters a syntax error\&.
Can also be raised from the action part of a grammar rule,
to initiate error recovery\&.

.sp

.I val set_trace 
: 
.B bool -> bool
.sp
Control debugging support for 
.ft B
ocamlyacc
.ft R
\-generated parsers\&.
After 
.ft B
Parsing\&.set_trace true
.ft R
, the pushdown automaton that
executes the parsers prints a trace of its actions (reading a token,
shifting a state, reducing by a rule) on standard output\&.
.ft B
Parsing\&.set_trace false
.ft R
turns this debugging trace off\&.
The boolean returned is the previous state of the trace flag\&.

.sp
.B "Since"
3.11.0

.sp