Added use of boost::optional<> to amount.h

17 files changed, 243 insertions, 118 deletions

diff --git a/Makefile.am b/Makefile.am
index ddf25d52..e7a7f455 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -27,7 +27,8 @@ AM_LFLAGS = -o $(LEX_OUTPUT_ROOT).c
 #WARNFLAGS += -Wconversion -Wshorten-64-to-32 -Wsign-compare
 #WARNFLAGS += -Wmissing-field-initializers -pedantic-errors
 
-libledger_la_CPPFLAGS = -I$(top_builddir)/gdtoa -I$(srcdir) -I$(srcdir)/src
+libledger_la_CPPFLAGS = -I$(top_builddir)/gdtoa -I$(srcdir)/gdtoa \
+			-I$(srcdir)/src
 libledger_la_LDFLAGS  = -release 3.0
 
 libledger_la_SOURCES = \
diff --git a/Makefile.in b/Makefile.in
index 9b1dbf56..6adae186 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -355,7 +355,7 @@ AM_LFLAGS = -o $(LEX_OUTPUT_ROOT).c
 #WARNFLAGS += -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion
 #WARNFLAGS += -Wconversion -Wshorten-64-to-32 -Wsign-compare
 #WARNFLAGS += -Wmissing-field-initializers -pedantic-errors
-libledger_la_CPPFLAGS = -I$(top_builddir)/gdtoa -I$(srcdir) \
+libledger_la_CPPFLAGS = -I$(top_builddir)/gdtoa -I$(srcdir)/gdtoa \
 	-I$(srcdir)/src $(am__append_2) $(am__append_4) \
 	$(am__append_6) $(am__append_8) $(am__append_9)
 libledger_la_LDFLAGS = -release 3.0
diff --git a/gdtoa/Makefile.am b/gdtoa/Makefile.am
index af0503da..232bc721 100644
--- a/gdtoa/Makefile.am
+++ b/gdtoa/Makefile.am
@@ -1,5 +1,6 @@
 lib_LTLIBRARIES = libgdtoa.la
 
+libgdtoa_la_LDFLAGS = -release 1.0
 libgdtoa_la_CPPFLAGS = -I$(top_builddir)
 libgdtoa_la_SOURCES = \
 	dmisc.c dtoa.c g_Qfmt.c g__fmt.c g_ddfmt.c g_dfmt.c g_ffmt.c \
@@ -11,7 +12,8 @@ libgdtoa_la_SOURCES = \
 
 EXTRA_libgdtoa_la_SOURCES = arithchk.c qnan.c
 
-$(libgdtoa_la_SOURCES): arith.h gd_qnan.h
+BUILT_SOURCES = arith.h gd_qnan.h
+CLEANFILES = arith.h gd_qnan.h arithchk qnan
 
 arith.h: arithchk.c
 	$(CC) $(CFLAGS) -o $(top_builddir)/arithchk $< || \
@@ -24,9 +26,4 @@ gd_qnan.h: qnan.c arith.h
 	$(top_builddir)/qnan > $(top_builddir)/$@
 	rm -f $(top_builddir)/qnan
 
-libgdtoa_la_LDFLAGS = -release 1.0
-
-pkginclude_HEADERS = gdtoa.h gdtoaimp.h
-
-CLEANFILES = arithchk qnan
-DISTCLEANFILES = arithchk arith.h qnan gd_qnan.h
+pkginclude_HEADERS = gdtoa.h gdtoaimp.h arith.h gd_qnan.h
diff --git a/gdtoa/Makefile.in b/gdtoa/Makefile.in
index c668a4ee..68e9b617 100644
--- a/gdtoa/Makefile.in
+++ b/gdtoa/Makefile.in
@@ -219,6 +219,7 @@ target_alias = @target_alias@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 lib_LTLIBRARIES = libgdtoa.la
+libgdtoa_la_LDFLAGS = -release 1.0
 libgdtoa_la_CPPFLAGS = -I$(top_builddir)
 libgdtoa_la_SOURCES = \
 	dmisc.c dtoa.c g_Qfmt.c g__fmt.c g_ddfmt.c g_dfmt.c g_ffmt.c \
@@ -229,11 +230,10 @@ libgdtoa_la_SOURCES = \
 	strtord.c strtordd.c strtorf.c strtorx.c strtorxL.c sum.c ulp.c
 
 EXTRA_libgdtoa_la_SOURCES = arithchk.c qnan.c
-libgdtoa_la_LDFLAGS = -release 1.0
-pkginclude_HEADERS = gdtoa.h gdtoaimp.h
-CLEANFILES = arithchk qnan
-DISTCLEANFILES = arithchk arith.h qnan gd_qnan.h
-all: acconf.h
+BUILT_SOURCES = arith.h gd_qnan.h
+CLEANFILES = arith.h gd_qnan.h arithchk qnan
+pkginclude_HEADERS = gdtoa.h gdtoaimp.h arith.h gd_qnan.h
+all: $(BUILT_SOURCES) acconf.h
 	$(MAKE) $(AM_MAKEFLAGS) all-am
 
 .SUFFIXES:
@@ -890,13 +890,15 @@ distcleancheck: distclean
 	       $(distcleancheck_listfiles) ; \
 	       exit 1; } >&2
 check-am: all-am
-check: check-am
+check: $(BUILT_SOURCES)
+	$(MAKE) $(AM_MAKEFLAGS) check-am
 all-am: Makefile $(LTLIBRARIES) $(HEADERS) acconf.h
 installdirs:
 	for dir in "$(DESTDIR)$(libdir)" "$(DESTDIR)$(pkgincludedir)"; do \
 	  test -z "$$dir" || $(MKDIR_P) "$$dir"; \
 	done
-install: install-am
+install: $(BUILT_SOURCES)
+	$(MAKE) $(AM_MAKEFLAGS) install-am
 install-exec: install-exec-am
 install-data: install-data-am
 uninstall: uninstall-am
@@ -917,11 +919,11 @@ clean-generic:
 
 distclean-generic:
 	-test -z "$(CONFIG_CLEAN_FILES)" || rm -f $(CONFIG_CLEAN_FILES)
-	-test -z "$(DISTCLEANFILES)" || rm -f $(DISTCLEANFILES)
 
 maintainer-clean-generic:
 	@echo "This command is intended for maintainers to use"
 	@echo "it deletes files that may require special tools to rebuild."
+	-test -z "$(BUILT_SOURCES)" || rm -f $(BUILT_SOURCES)
 clean: clean-am
 
 clean-am: clean-generic clean-libLTLIBRARIES clean-libtool \
@@ -1004,8 +1006,6 @@ uninstall-am: uninstall-libLTLIBRARIES uninstall-pkgincludeHEADERS
 	uninstall-libLTLIBRARIES uninstall-pkgincludeHEADERS
 
 
-$(libgdtoa_la_SOURCES): arith.h gd_qnan.h
-
 arith.h: arithchk.c
 	$(CC) $(CFLAGS) -o $(top_builddir)/arithchk $< || \
 	$(CC) -DNO_LONG_LONG $(CFLAGS) -o $(top_builddir)/arithchk $<
diff --git a/src/amount.cc b/src/amount.cc
index dabca4e4..6020a0aa 100644
--- a/src/amount.cc
+++ b/src/amount.cc
@@ -59,11 +59,13 @@ bool amount_t::full_strings = false;
 class amount_t::bigint_t
 {
  public:
-  mpz_t		val;
-  unsigned char prec;
-  unsigned char flags;
-  unsigned int	ref;
-  unsigned int	index;
+  typedef uint8_t precision_t;
+
+  mpz_t		 val;
+  precision_t	 prec;
+  uint8_t	 flags;
+  uint_least16_t ref;
+  uint_fast32_t	 index;
 
   bigint_t() : prec(0), flags(0), ref(1), index(0) {
     TRACE_CTOR(bigint_t, "");
@@ -245,7 +247,7 @@ amount_t::amount_t(const unsigned long val)
 }
 
 namespace {
-  unsigned char convert_double(mpz_t dest, double val)
+  amount_t::bigint_t::precision_t convert_double(mpz_t dest, double val)
   {
 #ifndef HAVE_GDTOA
     // This code is far too imprecise to be worthwhile.
@@ -285,7 +287,7 @@ namespace {
     mpz_set_str(dest, buf, 10);
     free(buf);
 
-    return (unsigned char)exp;
+    return amount_t::bigint_t::precision_t(exp);
 #else
     int decpt, sign;
     char * buf = dtoa(val, 0, 0, &decpt, &sign, NULL);
@@ -830,7 +832,7 @@ void amount_t::print_quantity(std::ostream& out) const
   // outputting it.  NOTE: `rquotient' is used here as a temp variable!
 
   commodity_t&  comm(commodity());
-  unsigned char precision;
+  bigint_t::precision_t precision;
 
   if (! comm || quantity->flags & BIGINT_KEEP_PREC) {
     mpz_ui_pow_ui(divisor, 10, quantity->prec);
@@ -932,7 +934,7 @@ void amount_t::print(std::ostream& _out, bool omit_commodity,
   // outputting it.  NOTE: `rquotient' is used here as a temp variable!
 
   commodity_t&	comm(base.commodity());
-  unsigned char precision = 0;
+  bigint_t::precision_t precision = 0;
 
   if (quantity) {
     if (! comm || full_precision || base.quantity->flags & BIGINT_KEEP_PREC) {
@@ -1213,7 +1215,7 @@ bool parse_annotations(std::istream& in, amount_t& price,
   return has_date;
 }
 
-void amount_t::parse(std::istream& in, unsigned char flags)
+void amount_t::parse(std::istream& in, uint8_t flags)
 {
   // The possible syntax for an amount is:
   //
@@ -1425,10 +1427,10 @@ void amount_t::write(std::ostream& out) const
 
 
 #ifndef THREADSAFE
-static char *	    bigints;
-static char *	    bigints_next;
-static unsigned int bigints_index;
-static unsigned int bigints_count;
+static char *	     bigints;
+static char *	     bigints_next;
+static uint_fast32_t bigints_index;
+static uint_fast32_t bigints_count;
 #endif
 
 void amount_t::read_quantity(char *& data)
@@ -1452,14 +1454,14 @@ void amount_t::read_quantity(char *& data)
     if (negative)
       mpz_neg(MPZ(quantity), MPZ(quantity));
 
-    quantity->prec = *((unsigned char *) data);
-    data += sizeof(unsigned char);
-    quantity->flags = *((unsigned char *) data);
-    data += sizeof(unsigned char);
+    quantity->prec = *((bigint_t::precision_t *) data);
+    data += sizeof(bigint_t::precision_t);
+    quantity->flags = *((uint8_t *) data);
+    data += sizeof(uint8_t);
     quantity->flags |= BIGINT_BULK_ALLOC;
   } else {
-    unsigned int index = *((unsigned int *) data);
-    data += sizeof(unsigned int);
+    uint_fast32_t index = *((uint_fast32_t *) data);
+    data += sizeof(uint_fast32_t);
 
     quantity = (bigint_t *) (bigints + (index - 1) * sizeof(bigint_t));
     DEBUG("amounts.refs",
@@ -1533,7 +1535,7 @@ void amount_t::write_quantity(std::ostream& out) const
     out.write(&byte, sizeof(byte));
 
     out.write((char *)&quantity->prec, sizeof(quantity->prec));
-    unsigned char flags = quantity->flags & ~BIGINT_BULK_ALLOC;
+    uint8_t flags = quantity->flags & ~BIGINT_BULK_ALLOC;
     assert(sizeof(flags) == sizeof(quantity->flags));
     out.write((char *)&flags, sizeof(flags));
   } else {
@@ -1634,7 +1636,7 @@ amount_t amount_t::strip_annotations(const bool _keep_price,
   return t;
 }
 
-amount_t amount_t::price() const
+optional<amount_t> amount_t::price() const
 {
   if (commodity_ && commodity_->annotated) {
     amount_t t(((annotated_commodity_t *)commodity_)->price);
@@ -1643,10 +1645,10 @@ amount_t amount_t::price() const
 	   "Returning price of " << *this << " = " << t);
     return t;
   }
-  return *this;
+  return optional<amount_t>();
 }
 
-moment_t amount_t::date() const
+optional<moment_t> amount_t::date() const
 {
   if (commodity_ && commodity_->annotated) {
     DEBUG("amounts.commodities",
@@ -1654,7 +1656,18 @@ moment_t amount_t::date() const
 	   << ((annotated_commodity_t *)commodity_)->date);
     return ((annotated_commodity_t *)commodity_)->date;
   }
-  return moment_t();
+  return optional<moment_t>();
+}
+
+optional<string> amount_t::tag() const
+{
+  if (commodity_ && commodity_->annotated) {
+    DEBUG("amounts.commodities",
+	   "Returning tag of " << *this << " = "
+	   << ((annotated_commodity_t *)commodity_)->tag);
+    return ((annotated_commodity_t *)commodity_)->tag;
+  }
+  return optional<string>();
 }
 
 
diff --git a/src/amount.h b/src/amount.h
index 3c8b03f6..84be02b3 100644
--- a/src/amount.h
+++ b/src/amount.h
@@ -48,7 +48,6 @@
 #define _AMOUNT_H
 
 #include "utils.h"
-#include "times.h"
 
 namespace ledger {
 
@@ -126,27 +125,34 @@ class amount_t
   }
 
   amount_t number() const {
+    if (! has_commodity())
+      return *this;
     amount_t temp(*this);
     temp.clear_commodity();
     return temp;
   }
 
   bool has_commodity() const;
-  commodity_t& commodity() const;
   void set_commodity(commodity_t& comm) {
     commodity_ = &comm;
   }
-  void annotate_commodity(const amount_t&    price,
-			  const moment_t&	     date = moment_t(),
-			  const string& tag  = "");
-  amount_t strip_annotations(const bool _keep_price = keep_price,
-			     const bool _keep_date  = keep_date,
-			     const bool _keep_tag   = keep_tag) const;
   void clear_commodity() {
     commodity_ = NULL;
   }
-  amount_t price() const;
-  moment_t date() const;
+
+  commodity_t& commodity() const;
+
+  void annotate_commodity(const amount_t& price,
+			  const moment_t& date = moment_t(),
+			  const string&	  tag  = "");
+
+  amount_t strip_annotations(const bool _keep_price = keep_price,
+			     const bool _keep_date  = keep_date,
+			     const bool _keep_tag   = keep_tag) const;
+
+  optional<amount_t> price() const;
+  optional<moment_t> date() const;
+  optional<string>   tag() const;
 
   bool null() const {
     return ! quantity && ! has_commodity();
@@ -247,7 +253,7 @@ class amount_t
   }
 
   // test for zero and non-zero
-  int sign() const;
+  int  sign() const;
   bool zero() const;
   bool realzero() const {
     return sign() == 0;
@@ -688,9 +694,9 @@ class annotated_commodity_t : public commodity_t
  public:
   const commodity_t * ptr;
 
-  amount_t    price;
-  moment_t  date;
-  string tag;
+  amount_t price;
+  moment_t date;
+  string   tag;
 
   explicit annotated_commodity_t() {
     TRACE_CTOR(annotated_commodity_t, "");
@@ -732,6 +738,8 @@ inline std::ostream& operator<<(std::ostream& out, const commodity_t& comm) {
 }
 
 inline amount_t amount_t::round() const {
+  if (! has_commodity())
+    return *this;
   return round(commodity().precision());
 }
 
@@ -740,10 +748,7 @@ inline bool amount_t::has_commodity() const {
 }
 
 inline commodity_t& amount_t::commodity() const {
-  if (! commodity_)
-    return *commodity_t::null_commodity;
-  else
-    return *commodity_;
+  return has_commodity() ? *commodity_ : *commodity_t::null_commodity;
 }
 
 void parse_conversion(const string& larger_str,
diff --git a/src/balance.cc b/src/balance.cc
index 73fd668c..462a7074 100644
--- a/src/balance.cc
+++ b/src/balance.cc
@@ -39,30 +39,51 @@ balance_t balance_t::value(const moment_t& moment) const
   return temp;
 }
 
-balance_t balance_t::price() const
+optional<balance_t> balance_t::price() const
 {
-  balance_t temp;
+  optional<balance_t> temp;
 
   for (amounts_map::const_iterator i = amounts.begin();
        i != amounts.end();
-       i++)
-    temp += (*i).second.price();
+       i++) {
+    optional<amount_t> i_price = (*i).second.price();
+    if (i_price) {
+      if (! temp)
+	temp = balance_t();
+      *temp += *i_price;
+    }
+  }
+  return temp;
+}
 
+optional<moment_t> balance_t::date() const
+{
+  optional<moment_t> temp;
+
+  for (amounts_map::const_iterator i = amounts.begin();
+       i != amounts.end();
+       i++) {
+    optional<moment_t> tdate = (*i).second.date();
+    if (! temp && tdate)
+      temp = *tdate;
+    else if (temp && tdate && temp != tdate)
+      return optional<moment_t>();
+  }
   return temp;
 }
 
-moment_t balance_t::date() const
+optional<string> balance_t::tag() const
 {
-  moment_t temp;
+  optional<string> temp;
 
   for (amounts_map::const_iterator i = amounts.begin();
        i != amounts.end();
        i++) {
-    moment_t tdate = (*i).second.date();
-    if (! is_valid_moment(temp) && is_valid_moment(tdate))
-      temp = tdate;
-    else if (temp != tdate)
-      return moment_t();
+    optional<string> ttag = (*i).second.tag();
+    if (! temp && ttag)
+      temp = *ttag;
+    else if (temp && ttag && temp != ttag)
+      return optional<string>();
   }
   return temp;
 }
diff --git a/src/balance.h b/src/balance.h
index 2a6f3072..e8665335 100644
--- a/src/balance.h
+++ b/src/balance.h
@@ -435,8 +435,10 @@ class balance_t
   amount_t  amount(const commodity_t& commodity = 
 		   *commodity_t::null_commodity) const;
   balance_t value(const moment_t& moment = now) const;
-  balance_t price() const;
-  moment_t     date() const;
+
+  optional<balance_t> price() const;
+  optional<moment_t>  date() const;
+  optional<string>    tag() const;
 
   balance_t
   strip_annotations(const bool keep_price = amount_t::keep_price,
@@ -896,12 +898,16 @@ class balance_pair_t
   balance_t value(const moment_t& moment = now) const {
     return quantity.value(moment);
   }
-  balance_t price() const {
+
+  optional<balance_t> price() const {
     return quantity.price();
   }
-  moment_t     date() const {
+  optional<moment_t>  date() const {
     return quantity.date();
   }
+  optional<string>    tag() const {
+    return quantity.tag();
+  }
 
   balance_t
   strip_annotations(const bool keep_price = amount_t::keep_price,
diff --git a/src/ledger.h b/src/ledger.h
index 2122ece3..a9c2e5b3 100644
--- a/src/ledger.h
+++ b/src/ledger.h
@@ -23,9 +23,6 @@
 #include <parser.h>
 #include <textual.h>
 #include <binary.h>
-#include <gnucash.h>
-#include <qif.h>
-#include <ofx.h>
 
 #include <report.h>
 #include <transform.h>
diff --git a/src/main.cc b/src/main.cc
index 506d17bb..0af4da0d 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -3,9 +3,12 @@
 #else
 #include <ledger.h>
 #endif
-#include <option.h>
 
 #include "acconf.h"
+#include "option.h"
+#include "gnucash.h"
+#include "qif.h"
+#include "ofx.h"
 
 #ifdef HAVE_UNIX_PIPES
 #include <sys/types.h>
diff --git a/src/system.hh b/src/system.hh
index a1c686c0..ce7a71be 100644
--- a/src/system.hh
+++ b/src/system.hh
@@ -82,7 +82,7 @@ namespace std {
 
 #define HAVE_GDTOA 1
 #ifdef HAVE_GDTOA
-#include <gdtoa/gdtoa.h>
+#include "gdtoa.h"
 #endif
 
 extern "C" {
diff --git a/src/times.cc b/src/times.cc
index 8966d598..a11d4d50 100644
--- a/src/times.cc
+++ b/src/times.cc
@@ -1,4 +1,4 @@
-#include "times.h"
+#include "utils.h"
 
 namespace ledger {
 
diff --git a/src/times.h b/src/times.h
index a05e5d74..78b942e0 100644
--- a/src/times.h
+++ b/src/times.h
@@ -1,8 +1,6 @@
 #ifndef _TIMES_H
 #define _TIMES_H
 
-#include "utils.h"
-
 namespace ledger {
 
 #define SUPPORT_DATE_AND_TIME 1
diff --git a/src/utils.cc b/src/utils.cc
index f37ec650..41bca6be 100644
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -1,5 +1,4 @@
 #include "utils.h"
-#include "times.h"
 
 /**********************************************************************
  *
diff --git a/src/utils.h b/src/utils.h
index 8be512fb..da6aaa27 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -5,6 +5,26 @@
 
 /**********************************************************************
  *
+ * Default values
+ */
+
+#if defined(FULL_DEBUG)
+#define VERIFY_ON   1
+#define TRACING_ON  1
+#define DEBUG_ON    1
+#define TIMERS_ON   1
+#define FREE_MEMORY 1
+#elif defined(NO_DEBUG)
+#define NO_ASSERTS  1
+#define NO_LOGGING  1
+#else
+#define VERIFY_ON   1		// compiled in, use --verify to enable
+#define TRACING_ON  1		// use --trace X to enable
+#define TIMERS_ON   1
+#endif
+
+/**********************************************************************
+ *
  * Forward declarations
  */
 
@@ -31,26 +51,6 @@ namespace ledger {
 
 /**********************************************************************
  *
- * Default values
- */
-
-#if defined(FULL_DEBUG)
-#define VERIFY_ON   1
-#define TRACING_ON  1
-#define DEBUG_ON    1
-#define TIMERS_ON   1
-#define FREE_MEMORY 1
-#elif defined(NO_DEBUG)
-#define NO_ASSERTS  1
-#define NO_LOGGING  1
-#else
-#define VERIFY_ON   1		// compiled in, use --verify to enable
-#define TRACING_ON  1		// use --trace X to enable
-#define TIMERS_ON   1		// jww (2007-04-25): is this correct?
-#endif
-
-/**********************************************************************
- *
  * Assertions
  */
 
@@ -72,6 +72,10 @@ namespace ledger {
   ((x) ? ((void)0) : debug_assert(#x, BOOST_CURRENT_FUNCTION,	\
 				  __FILE__, __LINE__))
 
+#else // ! ASSERTS_ON
+
+#define assert(x)
+
 #endif // ASSERTS_ON
 
 /**********************************************************************
@@ -431,6 +435,13 @@ inline void throw_unexpected_error(char c, char wanted) {
 
 /**********************************************************************
  *
+ * Date/time support classes
+ */
+
+#include "times.h"
+
+/**********************************************************************
+ *
  * General utility functions
  */
 
diff --git a/src/value.cc b/src/value.cc
index c5c67b34..74a3bd8f 100644
--- a/src/value.cc
+++ b/src/value.cc
@@ -1981,12 +1981,24 @@ value_t value_t::price() const
   case DATETIME:
     throw_(value_error, "Cannot find the price of a date/time");
 
-  case AMOUNT:
-    return ((amount_t *) data)->price();
-  case BALANCE:
-    return ((balance_t *) data)->price();
-  case BALANCE_PAIR:
-    return ((balance_pair_t *) data)->quantity.price();
+  case AMOUNT: {
+    optional<amount_t> temp = ((amount_t *) data)->price();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE: {
+    optional<balance_t> temp = ((balance_t *) data)->price();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE_PAIR: {
+    optional<balance_t> temp = ((balance_pair_t *) data)->price();
+    if (! temp)
+      return false;
+    return *temp;
+  }
 
   case STRING:
     throw_(value_error, "Cannot find the price of a string");
@@ -2018,12 +2030,73 @@ value_t value_t::date() const
   case DATETIME:
     return *this;
 
-  case AMOUNT:
-    return ((amount_t *) data)->date();
-  case BALANCE:
-    return ((balance_t *) data)->date();
-  case BALANCE_PAIR:
-    return ((balance_pair_t *) data)->quantity.date();
+  case AMOUNT: {
+    optional<moment_t> temp = ((amount_t *) data)->date();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE: {
+    optional<moment_t> temp = ((balance_t *) data)->date();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE_PAIR: {
+    optional<moment_t> temp = ((balance_pair_t *) data)->date();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+
+  case STRING:
+    throw_(value_error, "Cannot find the date of a string");
+
+  case XML_NODE:
+    return (*(xml::node_t **) data)->to_value().date();
+
+  case POINTER:
+    throw_(value_error, "Cannot find the date of a pointer");
+  case SEQUENCE:
+    throw_(value_error, "Cannot find the date of a sequence");
+
+  default:
+    assert(0);
+    break;
+  }
+  assert(0);
+  return value_t();
+}
+
+value_t value_t::tag() const
+{
+  switch (type) {
+  case BOOLEAN:
+    throw_(value_error, "Cannot find the date of a boolean");
+  case INTEGER:
+    throw_(value_error, "Cannot find the date of an integer");
+
+  case DATETIME:
+    return *this;
+
+  case AMOUNT: {
+    optional<string> temp = ((amount_t *) data)->tag();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE: {
+    optional<string> temp = ((balance_t *) data)->tag();
+    if (! temp)
+      return false;
+    return *temp;
+  }
+  case BALANCE_PAIR: {
+    optional<string> temp = ((balance_pair_t *) data)->tag();
+    if (! temp)
+      return false;
+    return *temp;
+  }
 
   case STRING:
     throw_(value_error, "Cannot find the date of a string");
diff --git a/src/value.h b/src/value.h
index f3a31c76..0737fac1 100644
--- a/src/value.h
+++ b/src/value.h
@@ -441,6 +441,7 @@ class value_t
   value_t cost() const;
   value_t price() const;
   value_t date() const;
+  value_t tag() const;
 
   value_t cast(type_t cast_type) const {
     value_t temp(*this);