1 files changed, 100 insertions, 0 deletions
diff --git a/maildrop/re.h b/maildrop/re.h
new file mode 100644
index 0000000..1c2d3ab
--- /dev/null
+++ b/maildrop/re.h
@@ -0,0 +1,100 @@
+#ifndef	re_h
+#define	re_h
+
+
+#include	"config.h"
+#include	<sys/types.h>
+#include	"funcs.h"
+#include	"reeval.h"
+
+class ReMatch;
+
+///////////////////////////////////////////////////////////////////////////
+//
+//  The Re class represents a regular expression.   The regular expression
+//  is translated into a non-deterministic automaton, stored as a list
+//  of RegExpNodes.
+//
+//  Then, one or more strings are matched against the regular expression.
+//
+//  The Re object may dynamically allocate another Re object in order to
+//  implement the ! operator.  Each ! operator introduces a dynamically-
+//  allocated Re object, which contains the next chained regular expression.
+//  Another ! operator causes another object to be allocated.
+//
+//  The ^ and $ anchors are implemented here.  The ABSENCE of a ^ anchor
+//  causes a dummy "[.\n]*" expression to be created in the first Re object,
+//  with the real expression being parsed in the 2nd Re object.
+//
+//  When a string is matched against a regular expression, when the current
+//  state includes a FINAL state, and there is a chained Re object, the
+//  remainder of the string gets matched against the chained Re object.
+//  If the chained matched succeeds, the entire match succeeds, otherwise,
+//  we continue matching the original string.
+//
+//  If a match is succesfull, MatchCount() may be called to return the number
+//  of characters that were matched.  If an ! operator is used, the optional
+//  argument to MatchCount(), if not null, can be used to call MatchCount()
+//  to return the count that the next expression matched.
+//
+///////////////////////////////////////////////////////////////////////////
+
+class	RegExpNode;
+
+class Re {
+
+	Re	*chainedre;		// Chained regular expression
+	Re	*prevre;
+	RegExpNode *nodes;		// Singly-linked list of nodes
+	RegExpNode *first;		// Starting node
+	RegExpNode *final;		// Final node
+	unsigned nextid;		// When creating, next ID to assign
+
+	RegExpNode	*allocnode();
+	const	char *expr, *origexpr;
+
+	// When matching:
+	int	matched;
+	off_t matchedpos;
+	ReEval	*curstate, *nextstate;
+	unsigned final_id;
+
+	int	curchar() { return ((int)(unsigned char)*expr); }
+	void	nextchar() { ++expr; }
+	int	casesensitive;
+	int	matchFull;
+	int	isCaret;
+	int	isDummy;
+public:
+	Re();
+	~Re();
+
+	int Compile(const char *, int, int &);
+			// Compile regular expression
+private:
+	int CompileS(const char *, int, int &);
+
+
+	void init();
+	RegExpNode **CompileAtom(RegExpNode **);
+	RegExpNode **CompileAtomString(RegExpNode **);
+	RegExpNode **CompileOrClause(RegExpNode **);
+	RegExpNode **CompileElement(RegExpNode **);
+	void is_sets(RegExpNode *);
+
+	int	parsechar();
+
+// Evaluation
+
+	ReEval	state1, state2;
+	unsigned charsmatched;
+public:
+	int	Match(ReMatch &);
+	unsigned MatchCount(Re **p =0) {
+					if (p) *p=chainedre;
+					return (charsmatched); }
+	int	IsDummy()	{ return (isDummy); }
+	int	IsAnchorStart()	{ return (isCaret); }
+} ;
+
+#endif