-- Summary of Pattern Matching Packages in GNAT Hierarchy --
------------------------------------------------------------
--- There are three related packages that perform pattern maching functions.
+-- There are three related packages that perform pattern matching functions.
-- the following is an outline of these packages, to help you determine
-- which is best for your needs.
-- ("ABC" or "AB") & ("DEF" or "CDE") & ("GH" or "IJ")
- -- would succeed, afer two anchor point moves:
+ -- would succeed, after two anchor point moves:
-- "ABABCDEIJKL"
-- ^^^^^^^
-- of the pattern, starting with zero occurrences. It is
-- thus equivalent to ("" or (P & ("" or (P & ("" ....)))).
-- The pattern P may contain any number of pattern elements
- -- including the use of alternatiion and concatenation.
+ -- including the use of alternation and concatenation.
-- Break(S) Where S is a string, matches a string of zero or more
-- characters up to but not including a break character
-- BreakX(S) Where S is a string, behaves exactly like Break(S) when
-- it first matches, but if a string is successfully matched,
- -- then a susequent failure causes an attempt to extend the
+ -- then a subsequent failure causes an attempt to extend the
-- matched string.
-- Fence(P) Where P is a pattern, attempts to match the pattern P
-- match proceeds, but on a subsequent failure, no attempt
-- is made to search for alternative matches of P. The
-- pattern P may contain any number of pattern elements
- -- including the use of alternatiion and concatenation.
+ -- including the use of alternation and concatenation.
-- Len(N) Where N is a natural number, matches the given number of
-- characters. For example, Len(10) matches any string that
-- NotAny(S) Where S is a string, matches a single character that is
-- not one of the characters of S. Fails if the current
- -- characer is one of the given set of characters.
+ -- character is one of the given set of characters.
-- NSpan(S) Where S is a string, matches a string of zero or more
-- characters that is among the characters given in the
-- if the language allowed, we would use in out parameters, but we are
-- not allowed to have in out parameters for functions. Instead we pass
-- actuals which must be variables, and with a bit of trickery in the
- -- body, manage to interprete them properly as though they were indeed
+ -- body, manage to interpret them properly as though they were indeed
-- in out parameters.
pragma Warnings (Off, VString_Var);
-- causes the entire match to be aborted if a subsequent failure occurs.
function Fence (P : Pattern) return Pattern;
- -- Constructs a pattern that first matches P. if P fails, then the
+ -- Constructs a pattern that first matches P. If P fails, then the
-- constructed pattern fails. If P succeeds, then the match proceeds,
-- but if subsequent failure occurs, alternatives in P are not sought.
-- The idea of Fence is that each time the pattern is matched, just
-- if the language allowed, we would use an in out parameter, but we are
-- not allowed to have in out parameters for functions. Instead we pass
-- actuals which must be variables, and with a bit of trickery in the
- -- body, manage to interprete them properly as though they were indeed
+ -- body, manage to interpret them properly as though they were indeed
-- in out parameters.
function Match
private
type PE;
- -- Pattern element, a pattern is a plex structure of PE's. This type
- -- is defined and sdescribed in the body of this package.
+ -- Pattern element, a pattern is a complex structure of PE's. This type
+ -- is defined and described in the body of this package.
type PE_Ptr is access all PE;
-- Pattern reference. PE's use PE_Ptr values to reference other PE's
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