Created a new stream.h file for dealing with output streaming.

11 files changed, 534 insertions, 243 deletions

diff --git a/Makefile.am b/Makefile.am
index 1b4df29d..2e0e0136 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -31,6 +31,7 @@ libledger_util_la_SOURCES =	 \
 	src/utils.cc	 \
 	src/times.cc	 \
 	src/mask.cc	 \
+	src/stream.cc	 \
 	src/binary.cc	 \
 	lib/sha1.cpp
 
@@ -116,6 +117,7 @@ pkginclude_HEADERS =			   \
 	src/error.h			   \
 	src/times.h			   \
 	src/mask.h			   \
+	src/stream.h			   \
 	src/binary.h			   \
 					   \
 	src/amount.h			   \
diff --git a/src/main.cc b/src/main.cc
index 2f51a5bf..dfbeeb75 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -45,12 +45,6 @@
 #include "ofx.h"
 #endif
 
-#ifdef HAVE_UNIX_PIPES
-#include <sys/types.h>
-#include <sys/wait.h>
-#include "fdstream.h"
-#endif
-
 namespace ledger {
   int read_and_report(ledger::report_t& report,
 		      int argc, char * argv[], char * envp[])
@@ -133,176 +127,58 @@ namespace ledger {
 
     TRACE_FINISH(arguments, 1);
 
-    // Configure the output stream
-
-#ifdef HAVE_UNIX_PIPES
-    int status, pfd[2];		// Pipe file descriptors
-#endif
-    report.output_stream = &std::cout;
-
-    if (report.output_file) {
-      report.output_stream = new ofstream(*report.output_file);
-    }
-#ifdef HAVE_UNIX_PIPES
-    else if (report.pager) {
-      status = pipe(pfd);
-      if (status == -1)
-	throw_(std::logic_error, "Failed to create pipe");
-
-      status = fork();
-      if (status < 0) {
-	throw_(std::logic_error, "Failed to fork child process");
-      }
-      else if (status == 0) {	// child
-	// Duplicate pipe's reading end into stdin
-	status = dup2(pfd[0], STDIN_FILENO);
-	if (status == -1)
-	  perror("dup2");
-
-	// Close unuseful file descriptors: the pipe's writing and
-	// reading ends (the latter is not needed anymore, after the
-	// duplication).
-	close(pfd[1]);
-	close(pfd[0]);
-
-	// Find command name: its the substring starting right of the
-	// rightmost '/' character in the pager pathname.  See manpage
-	// for strrchr.
-	execlp(report.pager->native_file_string().c_str(),
-	       basename(*report.pager).c_str(), NULL);
-	perror("execl");
-	exit(1);
-      }
-      else {			// parent
-	close(pfd[0]);
-	report.output_stream = new boost::fdostream(pfd[1]);
-      }
-    }
-#endif
-
     // Read the command word and see if it's any of the debugging commands
     // that Ledger supports.
 
-    std::ostream& out(*report.output_stream);
-
     string verb = *arg++;
 
-    if (verb == "parse") {
-      out << "--- Input text ---" << std::endl;
-      out << *arg << std::endl;
-
-      out << std::endl << "--- Text as parsed ---" << std::endl;
-      expr_t expr(*arg);
-      expr.print(out);
-      out << std::endl;
-
-      out << std::endl << "--- Expression tree ---" << std::endl;
-      expr.dump(out);
-
-      out << std::endl << "--- Calculated value ---" << std::endl;
-      expr.calc(report).print(out);
-      out << std::endl;
-
-      return 0;
-    }
-    else if (verb == "compile") {
-      out << "--- Input text ---" << std::endl;
-      out << *arg << std::endl;
-
-      out << std::endl << "--- Text as parsed ---" << std::endl;
-      expr_t expr(*arg);
-      expr.print(out);
-      out << std::endl;
-
-      out << std::endl << "--- Expression tree ---" << std::endl;
-      expr.dump(out);
-
-      expr.compile(report);
-
-      out << std::endl << "--- Compiled tree ---" << std::endl;
-      expr.dump(out);
-
-      out << std::endl << "--- Calculated value ---" << std::endl;
-      expr.calc(report).print(out);
-      out << std::endl;
-
-      return 0;
-    }
-    else if (verb == "eval") {
-      expr_t expr(*arg);
-      out << expr.calc(report).strip_annotations() << std::endl;
-      return 0;
-    }
-    else if (verb == "format") {
-      format_t fmt(*arg);
-      fmt.dump(out);
-      return 0;
-    }
-    else if (verb == "period") {
-      interval_t interval(*arg);
-
-      if (! is_valid(interval.begin)) {
-	out << "Time period has no beginning." << std::endl;
-      } else {
-	out << "begin: " << format_date(interval.begin) << std::endl;
-	out << "  end: " << format_date(interval.end) << std::endl;
-	out << std::endl;
-
-	date_t date = interval.first();
-
-	for (int i = 0; i < 20; i++) {
-	  out << std::right;
-	  out.width(2);
-
-	  out << i << ": " << format_date(date) << std::endl;
-
-	  date = interval.increment(date);
-	  if (is_valid(interval.end) && date >= interval.end)
-	    break;
-	}
-      }
-      return 0;
-    }
+    function_t command;
+    if (expr_t::ptr_op_t def = report.lookup(string("ledger_precmd_") + verb))
+      command = def->as_function();
 
     // Parse the initialization file, which can only be textual; then
-    // parse the journal data.
+    // parse the journal data.  But only do this if there was no
+    // "pre-command", which are always executed without doing any
+    // parsing.
 
-    INFO_START(journal, "Read journal file");
+    if (! command) {
+      INFO_START(journal, "Read journal file");
 
-    journal_t& journal(*session.create_journal());
+      journal_t& journal(*session.create_journal());
 
-    std::size_t count = session.read_data(journal, report.account);
-    if (count == 0)
-      throw_(parse_error, "Failed to locate any journal entries; "
-	     "did you specify a valid file with -f?");
+      std::size_t count = session.read_data(journal, report.account);
+      if (count == 0)
+	throw_(parse_error, "Failed to locate any journal entries; "
+	       "did you specify a valid file with -f?");
 
-    INFO_FINISH(journal);
+      INFO_FINISH(journal);
 
-    INFO("Found " << count << " entries");
+      INFO("Found " << count << " entries");
 
-    TRACE_FINISH(entry_text, 1);
-    TRACE_FINISH(entry_date, 1);
-    TRACE_FINISH(entry_details, 1);
-    TRACE_FINISH(entry_xacts, 1);
-    TRACE_FINISH(entries, 1);
-    TRACE_FINISH(parsing_total, 1);
+      TRACE_FINISH(entry_text, 1);
+      TRACE_FINISH(entry_details, 1);
+      TRACE_FINISH(entry_xacts, 1);
+      TRACE_FINISH(entries, 1);
+      TRACE_FINISH(session_parser, 1);
+      TRACE_FINISH(parsing_total, 1);
 
-    // Lookup the command object corresponding to the command verb.
+      // Lookup the command object corresponding to the command verb.
 
-    function_t command;
-    if (expr_t::ptr_op_t def = report.lookup(string("cmd_") + verb))
-      command = def->as_function();
+      if (expr_t::ptr_op_t def = report.lookup(string("ledger_cmd_") + verb))
+	command = def->as_function();
+    }
 
     if (! command)
       throw_(std::logic_error, string("Unrecognized command '") + verb + "'");
 
+#if 1
     // Patch up some of the reporting options based on what kind of
     // command it was.
 
     // jww (2008-08-14): This code really needs to be rationalized away
     // for 3.0.
 
-    if (verb[0] == 'p' || verb == "entry" || verb == "dump") {
+    if (verb == "print" || verb == "entry" || verb == "dump") {
       report.show_related     = true;
       report.show_all_related = true;
     }
@@ -340,6 +216,7 @@ namespace ledger {
 	report.display_predicate = "amount";
       }
     }
+#endif
 
     // Now setup the various formatting strings
 
@@ -357,6 +234,10 @@ namespace ledger {
     if (! report.report_period.empty() && ! report.sort_all)
       report.entry_sort = true;
 
+    // Setup the output stream, which might involve invoking the pager
+
+    report.output_stream.initialize(report.output_file, report.pager_path);
+
     // Create an argument scope containing the report command's
     // arguments, and then invoke the command.
 
@@ -384,23 +265,6 @@ namespace ledger {
     }
 #endif
 
-    // If the user specified a pager, wait for it to exit now
-
-#ifdef HAVE_UNIX_PIPES
-    if (! report.output_file && report.pager) {
-      checked_delete(report.output_stream);
-      close(pfd[1]);
-
-      // Wait for child to finish
-      wait(&status);
-      if (status & 0xffff != 0)
-	throw_(std::logic_error, "Something went wrong in the pager");
-    }
-#endif
-    else if (DO_VERIFY() && report.output_file) {
-      checked_delete(report.output_stream);
-    }
-
     return 0;
   }
 }
diff --git a/src/output.cc b/src/output.cc
index 372981ab..c24bf111 100644
--- a/src/output.cc
+++ b/src/output.cc
@@ -57,7 +57,7 @@ format_xacts::format_xacts(report_t& _report, const string& format)
 
 void format_xacts::operator()(xact_t& xact)
 {
-  std::ostream& out(*report.output_stream);
+  std::ostream& out(report.output_stream);
 
   if (! xact.has_xdata() ||
       ! xact.xdata().has_flags(XACT_EXT_DISPLAYED)) {
@@ -82,7 +82,7 @@ void format_xacts::operator()(xact_t& xact)
 void format_entries::format_last_entry()
 {
   bool		first = true;
-  std::ostream& out(*report.output_stream);
+  std::ostream& out(report.output_stream);
 
   foreach (xact_t * xact, last_entry->xacts) {
     if (xact->has_xdata() &&
@@ -144,7 +144,7 @@ void print_entry(std::ostream& out, const entry_base_t& entry_base,
 
 void format_accounts::flush()
 {
-  std::ostream& out(*report.output_stream);
+  std::ostream& out(report.output_stream);
 
   if (print_final_total) {
     assert(out);
@@ -168,7 +168,7 @@ void format_accounts::operator()(account_t& account)
     if (! account.parent) {
       account.xdata().add_flags(ACCOUNT_EXT_TO_DISPLAY);
     } else {
-      format.format(*report.output_stream, account);
+      format.format(report.output_stream, account);
       account.xdata().add_flags(ACCOUNT_EXT_DISPLAYED);
     }
   }
@@ -246,7 +246,7 @@ format_equity::format_equity(report_t& _report, const string& _format)
   entry_t header_entry;
   header_entry.payee = "Opening Balances";
   header_entry._date = current_date;
-  first_line_format.format(*report.output_stream, header_entry);
+  first_line_format.format(report.output_stream, header_entry);
 }
 
 void format_equity::flush()
@@ -254,7 +254,7 @@ void format_equity::flush()
   account_t summary(NULL, "Equity:Opening Balances");
 
   account_t::xdata_t& xdata(summary.xdata());
-  std::ostream&	      out(*report.output_stream);
+  std::ostream&	      out(report.output_stream);
   
   xdata.value = total.negate();
 
@@ -280,7 +280,7 @@ void format_equity::flush()
 
 void format_equity::operator()(account_t& account)
 {
-  std::ostream& out(*report.output_stream);
+  std::ostream& out(report.output_stream);
 
   if (display_account(account)) {
     if (account.has_xdata()) {
diff --git a/src/output.h b/src/output.h
index 4b23cabb..0d4e2072 100644
--- a/src/output.h
+++ b/src/output.h
@@ -55,7 +55,7 @@ public:
   }
 
   virtual void flush() {
-    report.output_stream->flush();
+    report.output_stream.flush();
   }
   virtual void operator()(xact_t& xact);
 };
diff --git a/src/report.cc b/src/report.cc
index 4b45577b..2c34fc5d 100644
--- a/src/report.cc
+++ b/src/report.cc
@@ -441,7 +441,7 @@ namespace {
   template <class Type        = xact_t,
 	    class handler_ptr = xact_handler_ptr,
 	    void (report_t::*report_method)(handler_ptr) =
-	    &report_t::xacts_report>
+	      &report_t::xacts_report>
   class reporter
   {
     shared_ptr<item_handler<Type> > handler;
@@ -464,6 +464,143 @@ namespace {
       return true;
     }
   };
+
+  value_t parse_command(call_scope_t& args)
+  {
+    var_t<string> arg(args, 0);
+
+    if (! arg) {
+      throw std::logic_error("Usage: parse TEXT");
+      return 1L;
+    }
+
+    report_t& report(find_scope<report_t>(args));
+    std::ostream& out(report.output_stream);
+
+    out << "--- Input text ---" << std::endl;
+    out << *arg << std::endl;
+
+    out << std::endl << "--- Text as parsed ---" << std::endl;
+    expr_t expr(*arg);
+    expr.print(out);
+    out << std::endl;
+
+    out << std::endl << "--- Expression tree ---" << std::endl;
+    expr.dump(out);
+
+    out << std::endl << "--- Calculated value ---" << std::endl;
+    expr.calc(args).print(out);
+    out << std::endl;
+
+    return 0L;
+  }
+
+  value_t compile_command(call_scope_t& args)
+  {
+    var_t<string> arg(args, 0);
+
+    if (! arg) {
+      throw std::logic_error("Usage: compile TEXT");
+      return 1L;
+    }
+
+    report_t& report(find_scope<report_t>(args));
+    std::ostream& out(report.output_stream);
+
+    out << "--- Input text ---" << std::endl;
+    out << *arg << std::endl;
+
+    out << std::endl << "--- Text as parsed ---" << std::endl;
+    expr_t expr(*arg);
+    expr.print(out);
+    out << std::endl;
+
+    out << std::endl << "--- Expression tree ---" << std::endl;
+    expr.dump(out);
+
+    expr.compile(args);
+
+    out << std::endl << "--- Compiled tree ---" << std::endl;
+    expr.dump(out);
+
+    out << std::endl << "--- Calculated value ---" << std::endl;
+    expr.calc(args).print(out);
+    out << std::endl;
+
+    return 0L;
+  }
+
+  value_t eval_command(call_scope_t& args)
+  {
+    var_t<string> arg(args, 0);
+
+    if (! arg) {
+      throw std::logic_error("Usage: eval TEXT");
+      return 1L;
+    }
+
+    report_t& report(find_scope<report_t>(args));
+    std::ostream& out(report.output_stream);
+
+    expr_t expr(*arg);
+    out << expr.calc(args).strip_annotations() << std::endl;
+    return 0L;
+  }
+
+  value_t format_command(call_scope_t& args)
+  {
+    var_t<string> arg(args, 0);
+
+    if (! arg) {
+      throw std::logic_error("Usage: format TEXT");
+      return 1L;
+    }
+
+    report_t& report(find_scope<report_t>(args));
+    std::ostream& out(report.output_stream);
+
+    format_t fmt(*arg);
+    fmt.dump(out);
+
+    return 0L;
+  }
+
+  value_t period_command(call_scope_t& args)
+  {
+    var_t<string> arg(args, 0);
+
+    if (! arg) {
+      throw std::logic_error("Usage: period TEXT");
+      return 1L;
+    }
+
+    report_t& report(find_scope<report_t>(args));
+    std::ostream& out(report.output_stream);
+
+    interval_t interval(*arg);
+
+    if (! is_valid(interval.begin)) {
+      out << "Time period has no beginning." << std::endl;
+    } else {
+      out << "begin: " << format_date(interval.begin) << std::endl;
+      out << "  end: " << format_date(interval.end) << std::endl;
+      out << std::endl;
+
+      date_t date = interval.first();
+
+      for (int i = 0; i < 20; i++) {
+	out << std::right;
+	out.width(2);
+
+	out << i << ": " << format_date(date) << std::endl;
+
+	date = interval.increment(date);
+	if (is_valid(interval.end) && date >= interval.end)
+	  break;
+      }
+    }
+    return 0L;
+  }
 }
 
 expr_t::ptr_op_t report_t::lookup(const string& name)
@@ -475,8 +612,13 @@ expr_t::ptr_op_t report_t::lookup(const string& name)
       return MAKE_FUNCTOR(report_t::get_amount_expr);
     break;
 
-  case 'c':
-    if (std::strncmp(p, "cmd_", 4) == 0) {
+  case 'd':
+    if (std::strcmp(p, "display_total") == 0)
+	return MAKE_FUNCTOR(report_t::get_display_total);
+    break;
+
+  case 'l':
+    if (std::strncmp(p, "ledger_cmd_", 11) == 0) {
 
 #define FORMAT(str) \
     (format_string.empty() ? session. str : format_string)
@@ -494,7 +636,7 @@ expr_t::ptr_op_t report_t::lookup(const string& name)
       // xml
 #endif
 
-      p = p + 4;
+      p = p + 11;
       switch (*p) {
       case 'b':
 	if (*(p + 1) == '\0' ||
@@ -528,11 +670,6 @@ expr_t::ptr_op_t report_t::lookup(const string& name)
     }
     break;
 
-  case 'd':
-    if (std::strcmp(p, "display_total") == 0)
-	return MAKE_FUNCTOR(report_t::get_display_total);
-    break;
-
   case 'm':
     if (std::strcmp(p, "market_value") == 0)
       return MAKE_FUNCTOR(report_t::f_market_value);
@@ -782,7 +919,33 @@ expr_t::ptr_op_t report_t::lookup(const string& name)
     break;
 
   case 'p':
-    if (std::strcmp(p, "print_balance") == 0)
+    if (std::strncmp(p, "ledger_precmd_", 14) == 0) {
+      p = p + 14;
+      switch (*p) {
+      case 'p':
+	if (std::strcmp(p, "parse") == 0)
+	  return WRAP_FUNCTOR(parse_command);
+	else if (std::strcmp(p, "period") == 0)
+	  return WRAP_FUNCTOR(period_command);
+	break;
+
+      case 'c':
+	if (std::strcmp(p, "compile") == 0)
+	  return WRAP_FUNCTOR(compile_command);
+	break;
+
+      case 'e':
+	if (std::strcmp(p, "eval") == 0)
+	  return WRAP_FUNCTOR(eval_command);
+	break;
+
+      case 'f':
+	if (std::strcmp(p, "format") == 0)
+	  return WRAP_FUNCTOR(format_command);
+	break;
+      }
+    }
+    else if (std::strcmp(p, "print_balance") == 0)
       return WRAP_FUNCTOR(print_balance);
     break;
 
diff --git a/src/report.h b/src/report.h
index 59380949..6fcdc3f7 100644
--- a/src/report.h
+++ b/src/report.h
@@ -86,57 +86,57 @@ class report_t : public noncopyable, public scope_t
   report_t();
 
 public:
-  optional<path> output_file;
-  std::ostream * output_stream;
-
-  string	 format_string;
-  string	 date_output_format;
-  string	 predicate;
-  string	 secondary_predicate;
-  string	 display_predicate;
-  string	 report_period;
-  string	 report_period_sort;
-  string	 sort_string;
-  string	 descend_expr;
-  string	 forecast_limit;
-  string	 reconcile_balance;
-  string	 reconcile_date;
-
-  expr_t	 amount_expr;
-  expr_t	 total_expr;
-  expr_t	 display_total;
-
-  unsigned long  budget_flags;
-
-  long		 head_entries;
-  long		 tail_entries;
-
-  bool		 show_collapsed;
-  bool		 show_subtotal;
-  bool		 show_totals;
-  bool		 show_related;
-  bool		 show_all_related;
-  bool		 show_inverted;
-  bool		 show_empty;
-  bool		 days_of_the_week;
-  bool		 by_payee;
-  bool		 comm_as_payee;
-  bool		 code_as_payee;
-  bool		 show_revalued;
-  bool		 show_revalued_only;
-  bool		 keep_price;
-  bool		 keep_date;
-  bool		 keep_tag;
-  bool		 entry_sort;
-  bool		 sort_all;
-  bool		 anonymize;
-
-  string	 account;
-  optional<path> pager;
-
-  bool           raw_mode;
-
-  session_t&	 session;
+  optional<path>  output_file;
+  output_stream_t output_stream;
+
+  string	  format_string;
+  string	  date_output_format;
+  string	  predicate;
+  string	  secondary_predicate;
+  string	  display_predicate;
+  string	  report_period;
+  string	  report_period_sort;
+  string	  sort_string;
+  string	  descend_expr;
+  string	  forecast_limit;
+  string	  reconcile_balance;
+  string	  reconcile_date;
+
+  expr_t	  amount_expr;
+  expr_t	  total_expr;
+  expr_t	  display_total;
+
+  unsigned long	  budget_flags;
+
+  long		  head_entries;
+  long		  tail_entries;
+
+  bool		  show_collapsed;
+  bool		  show_subtotal;
+  bool		  show_totals;
+  bool		  show_related;
+  bool		  show_all_related;
+  bool		  show_inverted;
+  bool		  show_empty;
+  bool		  days_of_the_week;
+  bool		  by_payee;
+  bool		  comm_as_payee;
+  bool		  code_as_payee;
+  bool		  show_revalued;
+  bool		  show_revalued_only;
+  bool		  keep_price;
+  bool		  keep_date;
+  bool		  keep_tag;
+  bool		  entry_sort;
+  bool		  sort_all;
+  bool		  anonymize;
+
+  string	  account;
+  optional<path>  pager_path;
+
+  bool		  raw_mode;
+
+  session_t&	  session;
 
   explicit report_t(session_t& _session)
     : amount_expr("amount"),
@@ -426,11 +426,12 @@ public:
     return true;
   }
 
-#if 0
   value_t option_pager(call_scope_t& args) { // :
-    config->pager = optarg;
+    pager_path = args[0].as_string();
+    return true;
   }
 
+#if 0
   value_t option_truncate(call_scope_t& args) { // :
     std::string style(optarg);
     if (style == "leading")
diff --git a/src/stream.cc b/src/stream.cc
new file mode 100644
index 00000000..0394c042
--- /dev/null
+++ b/src/stream.cc
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2003-2009, John Wiegley.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of New Artisans LLC nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "utils.h"
+
+#ifdef HAVE_UNIX_PIPES
+#include <sys/types.h>
+#include <sys/wait.h>
+#include "fdstream.h"
+#endif
+
+namespace ledger {
+
+namespace {
+  /**
+   * @brief Forks a child process so that Ledger may handle running a
+   * pager
+   *
+   * In order for the pager option to work, Ledger has to run the pager
+   * itself, which requires Ledger to fork a new process in order to run
+   * the pager.  This function does the necessary fork.  After the fork,
+   * two processes exist.  One of them is exec'd to create the pager;
+   * the other is still Ledger.
+   *
+   * This function returns only for the process that is still Ledger.
+   *
+   * @param out Pointer to a pointer to the output stream.  This The
+   * pointer to the output stream is changed so that the stream is
+   * connected to the stdin of the pager.  The caller is responsible for
+   * cleaning this up.
+   *
+   * @param pager_path Path to the pager command.
+   *
+   * @return The file descriptor of the pipe to the pager.  The caller
+   * is responsible for cleaning this up.
+   *
+   * @exception std::logic_error Some problem was encountered, such as
+   * failure to create a pipe or failure to fork a child process.
+   */
+  int do_fork(std::ostream ** os, const path& pager_path)
+  {
+    int pfd[2];
+
+    int status = pipe(pfd);
+    if (status == -1)
+      throw std::logic_error("Failed to create pipe");
+
+    status = fork();
+    if (status < 0) {
+      throw std::logic_error("Failed to fork child process");
+    }
+    else if (status == 0) {	// child
+      const char *arg0;
+
+      // Duplicate pipe's reading end into stdin
+      status = dup2(pfd[0], STDIN_FILENO);
+      if (status == -1)
+	perror("dup2");
+
+      // Close unuseful file descriptors: the pipe's writing and reading
+      // ends (the latter is not needed anymore, after the duplication).
+      close(pfd[1]);
+      close(pfd[0]);
+
+      // Find command name: its the substring starting right of the
+      // rightmost '/' character in the pager pathname.  See manpage for
+      // strrchr.
+      path basename(pager_path.leaf());
+      execlp(pager_path.string().c_str(), basename.string().c_str(),
+	     (char *)0);
+
+      // We should never, ever reach here
+      perror("execl");
+      exit(1);
+    }
+    else {			// parent
+      close(pfd[0]);
+      *os = new boost::fdostream(pfd[1]);
+    }
+    return pfd[1];
+  }
+}
+
+void output_stream_t::initialize(const optional<path>& output_file,
+				 const optional<path>& pager_path)
+{
+  TRACE_CTOR(output_stream_t, "const path&, const path&");
+
+  if (output_file)
+    os = new ofstream(*output_file);
+  else if (pager_path && exists(*pager_path))
+    pipe_to_pager_fd = do_fork(&os, *pager_path);
+  else
+    os = &std::cout;
+}
+
+output_stream_t::~output_stream_t()
+{
+  TRACE_DTOR(output_stream_t);
+
+  if (os && os != &std::cout)
+    checked_delete(os);
+
+  if (pipe_to_pager_fd != -1) {
+    close(pipe_to_pager_fd);
+
+    int status;
+    wait(&status);
+    if (status & 0xffff != 0)
+      throw std::logic_error("Something went wrong in the pager");
+  }
+}
+
+} // namespace ledger
diff --git a/src/stream.h b/src/stream.h
new file mode 100644
index 00000000..3c8364b0
--- /dev/null
+++ b/src/stream.h
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2003-2009, John Wiegley.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of New Artisans LLC nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @addtogroup util
+ */
+
+/**
+ * @file   stream.h
+ * @author John Wiegley, Omari Norman
+ *
+ * @ingroup util
+ *
+ * @brief A utility class for abstracting an output stream.
+ *
+ * Because Ledger might send output to a file, the console, or a pager
+ * child process, different cleanup is needed for each scenario.  This
+ * file abstracts those various needs.
+ */
+
+#ifndef _STREAM_H
+#define _STREAM_H
+
+namespace ledger {
+
+/**
+ * @brief An output stream
+ *
+ * A stream to output in Ledger may be going to one of three places:
+ * to stdout, to a file, or to a pager. Construct an output_stream_t and
+ * the stream will automatically be cleaned up upon destruction.
+ *
+ * This class suffers from "else-if-heimer's disease," see Marshall
+ * Cline's "C++ FAQ Lite". Arguably this should be three different
+ * classes, but that introduces additional unneeded complications.
+ */
+class output_stream_t
+{
+private:
+  int pipe_to_pager_fd;
+
+public:
+  /**
+   * A pointer to the ostream.  Don't delete this; the output_stream_t
+   * class takes care of this.
+   */
+  std::ostream * os;
+
+  /**
+   * Construct a new output_stream_t.
+   *
+   * @param output_file File to which to send output. If both this
+   * and pager are set, output_file takes priority.
+   *
+   * @param pager Path to a pager. To not use a pager, leave this
+   * empty.
+   */
+  output_stream_t() : pipe_to_pager_fd(-1), os(NULL) {
+    TRACE_CTOR(output_stream_t, "");
+  }
+
+  void initialize(const optional<path>& output_file = none,
+		  const optional<path>& pager_path  = none);
+
+  /**
+   * Destroys an output_stream_t.  This deletes the dynamically
+   * allocated ostream, if necessary. It also closes output file
+   * descriptor, if necessary.
+   */
+  ~output_stream_t();
+
+  /**
+   * Convertor to a standard ostream.  This is used so that we can
+   * stream directly to an object of type output_stream_t.
+   */
+  operator std::ostream&() {
+    return *os;
+  }
+
+  /**
+   * Flushing function.  A simple proxy for ostream's flush.
+   */
+  void flush() {
+    os->flush();
+  }
+};
+
+} // namespace ledger
+
+#endif // _STREAM_H
diff --git a/src/utils.h b/src/utils.h
index 248b59df..16bcd09d 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -471,6 +471,7 @@ void finish_timer(const char * name);
 #include "error.h"
 #include "times.h"
 #include "flags.h"
+#include "stream.h"
 #include "pushvar.h"
 
 /**
diff --git a/src/xml.cc b/src/xml.cc
index 3ab3a5e3..99e4f1c5 100644
--- a/src/xml.cc
+++ b/src/xml.cc
@@ -400,7 +400,7 @@ void output_xml_string(std::ostream& out, const string& str)
 
 void format_xml_entries::format_last_entry()
 {
-  std::ostream& out(*report.output_stream);
+  std::ostream& out(report.output_stream);
 
 #if 0
   // jww (2008-05-08): Need to format these dates
diff --git a/src/xml.h b/src/xml.h
index a8fa242e..6a9b4a08 100644
--- a/src/xml.h
+++ b/src/xml.h
@@ -93,8 +93,8 @@ public:
 		     const bool _show_totals = false)
     : format_entries(_report, ""), show_totals(_show_totals) {
     TRACE_CTOR(format_xml_entries, "std::ostream&, const bool");
-    *report.output_stream << "<?xml version=\"1.0\"?>\n"
-			  << "<ledger version=\"2.5\">\n";
+    report.output_stream << "<?xml version=\"1.0\"?>\n"
+			 << "<ledger version=\"2.5\">\n";
   }
   virtual ~format_xml_entries() throw() {
     TRACE_DTOR(format_xml_entries);
@@ -102,7 +102,7 @@ public:
 
   virtual void flush() {
     format_entries::flush();
-    *report.output_stream << "</ledger>" << std::endl;
+    report.output_stream << "</ledger>" << std::endl;
   }
 
   virtual void format_last_entry();