Get `gn gen` to succeed on Windows

third_party/sqlite/src/tool/split-sqlite3c.tcl

+#!/usr/bin/tclsh
+#
+# This script splits the sqlite3.c amalgamated source code files into
+# several smaller files such that no single files is more than a fixed
+# number of lines in length (32k or 64k).  Each of the split out files
+# is #include-ed by the master file.
+#
+# Splitting files up this way allows them to be used with older compilers
+# that cannot handle really long source files.
+#
+set MAX 32768    ;# Maximum number of lines per file.
+
+set BEGIN {^/\*+ Begin file ([a-zA-Z0-9_.]+) \*+/}
+set END   {^/\*+ End of %s \*+/}
+
+set in [open sqlite3.c]
+set out1 [open sqlite3-all.c w]
+
+# Copy the header from sqlite3.c into sqlite3-all.c
+#
+while {[gets $in line]} {
+  if {[regexp $BEGIN $line]} break
+  puts $out1 $line
+}
+
+# Gather the complete content of a file into memory.  Store the
+# content in $bufout.  Store the number of lines is $nout
+#
+proc gather_one_file {firstline bufout nout} {
+  regexp $::BEGIN $firstline all filename
+  set end [format $::END $filename]
+  upvar $bufout buf $nout n
+  set buf $firstline\n
+  global in
+  set n 0
+  while {[gets $in line]>=0} {
+    incr n
+    append buf $line\n
+    if {[regexp $end $line]} break
+  }
+}
+
+# Write a big chunk of text in to an auxiliary file "sqlite3-NNN.c".
+# Also add an appropriate #include to sqlite3-all.c
+#
+set filecnt 0
+proc write_one_file {content} {
+  global filecnt
+  incr filecnt
+  set out [open sqlite3-$filecnt.c w]
+  puts -nonewline $out $content
+  close $out
+  puts $::out1 "#include \"sqlite3-$filecnt.c\""
+}
+
+# Continue reading input.  Store chunks in separate files and add
+# the #includes to the main sqlite3-all.c file as necessary to reference
+# the extra chunks.
+#
+set all {}
+set N 0
+while {[regexp $BEGIN $line]} {
+  set buf {}
+  set n 0
+  gather_one_file $line buf n
+  if {$n+$N>=$MAX} {
+    write_one_file $all
+    set all {}
+    set N 0
+  }
+  append all $buf
+  incr N $n
+  while {[gets $in line]>=0} {
+    if {[regexp $BEGIN $line]} break
+    puts $out1 $line
+  }
+}
+if {$N>0} {
+  write_one_file $all
+}
+close $out1
+close $in