Add option to use box-draw chars with --tree

This picks up and hopefully completes PR #3560.

Add documentation for new --tree "linedraw" option.
  There is a new example output in userguide, which renumbers
  several of the existing troubleshoot_tree example outputs.
Test is cleaned up a bit (not just the added part).
The actual function in Util is made a little more genral -
  it uses unicode chr() values instead of literally pasting
  in the line drawing characters.

Signed-off-by: Mats Wichmann <mats@linux.com>

9 files changed, 151 insertions, 130 deletions

diff --git a/doc/generated/examples/troubleshoot_tree1_2.xml b/doc/generated/examples/troubleshoot_tree1_2.xml
index 0bd4874..d99435d 100644
--- a/doc/generated/examples/troubleshoot_tree1_2.xml
+++ b/doc/generated/examples/troubleshoot_tree1_2.xml
@@ -1,7 +1,31 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<screen xmlns="http://www.scons.org/dbxsd/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=all f2.o</userinput>
+<screen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.scons.org/dbxsd/v1.0" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=all,linedraw</userinput>
+cc -o f1.o -c -I. f1.c
 cc -o f2.o -c -I. f2.c
-+-f2.o
-  +-f2.c
-  +-inc.h
+cc -o f3.o -c -I. f3.c
+cc -o prog f1.o f2.o f3.o
+└─┬.
+  ├─SConstruct
+  ├─f1.c
+  ├─┬f1.o
+  │ ├─f1.c
+  │ └─inc.h
+  ├─f2.c
+  ├─┬f2.o
+  │ ├─f2.c
+  │ └─inc.h
+  ├─f3.c
+  ├─┬f3.o
+  │ ├─f3.c
+  │ └─inc.h
+  ├─inc.h
+  └─┬prog
+    ├─┬f1.o
+    │ ├─f1.c
+    │ └─inc.h
+    ├─┬f2.o
+    │ ├─f2.c
+    │ └─inc.h
+    └─┬f3.o
+      ├─f3.c
+      └─inc.h
 </screen>
diff --git a/doc/generated/examples/troubleshoot_tree1_3.xml b/doc/generated/examples/troubleshoot_tree1_3.xml
index 75fa841..7f3789f 100644
--- a/doc/generated/examples/troubleshoot_tree1_3.xml
+++ b/doc/generated/examples/troubleshoot_tree1_3.xml
@@ -1,11 +1,6 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<screen xmlns="http://www.scons.org/dbxsd/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=all f1.o f3.o</userinput>
-cc -o f1.o -c -I. f1.c
-+-f1.o
-  +-f1.c
-  +-inc.h
-cc -o f3.o -c -I. f3.c
-+-f3.o
-  +-f3.c
+<screen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.scons.org/dbxsd/v1.0" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=all f2.o</userinput>
+cc -o f2.o -c -I. f2.c
++-f2.o
+  +-f2.c
   +-inc.h
 </screen>
diff --git a/doc/generated/examples/troubleshoot_tree1_4.xml b/doc/generated/examples/troubleshoot_tree1_4.xml
index 409bce9..bc0dbac 100644
--- a/doc/generated/examples/troubleshoot_tree1_4.xml
+++ b/doc/generated/examples/troubleshoot_tree1_4.xml
@@ -1,43 +1,10 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<screen xmlns="http://www.scons.org/dbxsd/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=status</userinput>
+<screen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.scons.org/dbxsd/v1.0" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=all f1.o f3.o</userinput>
 cc -o f1.o -c -I. f1.c
-cc -o f2.o -c -I. f2.c
++-f1.o
+  +-f1.c
+  +-inc.h
 cc -o f3.o -c -I. f3.c
-cc -o prog f1.o f2.o f3.o
- E         = exists
-  R        = exists in repository only
-   b       = implicit builder
-   B       = explicit builder
-    S      = side effect
-     P     = precious
-      A    = always build
-       C   = current
-        N  = no clean
-         H = no cache
-
-[E b      ]+-.
-[E     C  ]  +-SConstruct
-[E     C  ]  +-f1.c
-[E B   C  ]  +-f1.o
-[E     C  ]  | +-f1.c
-[E     C  ]  | +-inc.h
-[E     C  ]  +-f2.c
-[E B   C  ]  +-f2.o
-[E     C  ]  | +-f2.c
-[E     C  ]  | +-inc.h
-[E     C  ]  +-f3.c
-[E B   C  ]  +-f3.o
-[E     C  ]  | +-f3.c
-[E     C  ]  | +-inc.h
-[E     C  ]  +-inc.h
-[E B   C  ]  +-prog
-[E B   C  ]    +-f1.o
-[E     C  ]    | +-f1.c
-[E     C  ]    | +-inc.h
-[E B   C  ]    +-f2.o
-[E     C  ]    | +-f2.c
-[E     C  ]    | +-inc.h
-[E B   C  ]    +-f3.o
-[E     C  ]      +-f3.c
-[E     C  ]      +-inc.h
++-f3.o
+  +-f3.c
+  +-inc.h
 </screen>
diff --git a/doc/generated/examples/troubleshoot_tree1_5.xml b/doc/generated/examples/troubleshoot_tree1_5.xml
index b852ab0..687b1ba 100644
--- a/doc/generated/examples/troubleshoot_tree1_5.xml
+++ b/doc/generated/examples/troubleshoot_tree1_5.xml
@@ -1,15 +1,42 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<screen xmlns="http://www.scons.org/dbxsd/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=derived</userinput>
+<screen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.scons.org/dbxsd/v1.0" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=status</userinput>
 cc -o f1.o -c -I. f1.c
 cc -o f2.o -c -I. f2.c
 cc -o f3.o -c -I. f3.c
 cc -o prog f1.o f2.o f3.o
-+-.
-  +-f1.o
-  +-f2.o
-  +-f3.o
-  +-prog
-    +-f1.o
-    +-f2.o
-    +-f3.o
+ E         = exists
+  R        = exists in repository only
+   b       = implicit builder
+   B       = explicit builder
+    S      = side effect
+     P     = precious
+      A    = always build
+       C   = current
+        N  = no clean
+         H = no cache
+
+[E b      ]+-.
+[E     C  ]  +-SConstruct
+[E     C  ]  +-f1.c
+[E B   C  ]  +-f1.o
+[E     C  ]  | +-f1.c
+[E     C  ]  | +-inc.h
+[E     C  ]  +-f2.c
+[E B   C  ]  +-f2.o
+[E     C  ]  | +-f2.c
+[E     C  ]  | +-inc.h
+[E     C  ]  +-f3.c
+[E B   C  ]  +-f3.o
+[E     C  ]  | +-f3.c
+[E     C  ]  | +-inc.h
+[E     C  ]  +-inc.h
+[E B   C  ]  +-prog
+[E B   C  ]    +-f1.o
+[E     C  ]    | +-f1.c
+[E     C  ]    | +-inc.h
+[E B   C  ]    +-f2.o
+[E     C  ]    | +-f2.c
+[E     C  ]    | +-inc.h
+[E B   C  ]    +-f3.o
+[E     C  ]      +-f3.c
+[E     C  ]      +-inc.h
 </screen>
diff --git a/doc/generated/examples/troubleshoot_tree1_6.xml b/doc/generated/examples/troubleshoot_tree1_6.xml
index a0d42d7..00b05ac 100644
--- a/doc/generated/examples/troubleshoot_tree1_6.xml
+++ b/doc/generated/examples/troubleshoot_tree1_6.xml
@@ -1,26 +1,14 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<screen xmlns="http://www.scons.org/dbxsd/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=derived,status</userinput>
+<screen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.scons.org/dbxsd/v1.0" xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">% <userinput>scons -Q --tree=derived</userinput>
 cc -o f1.o -c -I. f1.c
 cc -o f2.o -c -I. f2.c
 cc -o f3.o -c -I. f3.c
 cc -o prog f1.o f2.o f3.o
- E         = exists
-  R        = exists in repository only
-   b       = implicit builder
-   B       = explicit builder
-    S      = side effect
-     P     = precious
-      A    = always build
-       C   = current
-        N  = no clean
-         H = no cache
-
-[E b      ]+-.
-[E B   C  ]  +-f1.o
-[E B   C  ]  +-f2.o
-[E B   C  ]  +-f3.o
-[E B   C  ]  +-prog
-[E B   C  ]    +-f1.o
-[E B   C  ]    +-f2.o
-[E B   C  ]    +-f3.o
++-.
+  +-f1.o
+  +-f2.o
+  +-f3.o
+  +-prog
+    +-f1.o
+    +-f2.o
+    +-f3.o
 </screen>
diff --git a/doc/man/scons.xml b/doc/man/scons.xml
index bfc4fd7..3d2abdf 100644
--- a/doc/man/scons.xml
+++ b/doc/man/scons.xml
@@ -1709,6 +1709,19 @@ not source files.</para>
   </varlistentry>
 
   <varlistentry>
+  <term><emphasis role="bold">linedraw</emphasis></term>
+  <listitem>
+<para>Draw the tree output using Unicode line-drawing characters
+instead of plain ASCII text. This option acts as a modifier
+to the selected <replaceable>type</replaceable>(s). If
+specified alone, without any <replaceable>type</replaceable>,
+it behaves as if <emphasis role="bold">all</emphasis>
+had been specified.
+</para>
+  </listitem>
+  </varlistentry>
+
+  <varlistentry>
   <term><emphasis role="bold">status</emphasis></term>
   <listitem>
 <para>Prints status information for each displayed node.</para>
@@ -6844,7 +6857,7 @@ env.PDFBuilder(target = 'bar', source = 'bar')
 <para>Note also that the above initialization
 overwrites the default Builder objects,
 so the Environment created above
-can not be used call Builders like 
+can not be used call Builders like
 <methodname>env.Program</methodname>,
 <methodname>env.Object</methodname>,
 <methodname>env.StaticLibrary</methodname> etc.</para>
diff --git a/doc/user/troubleshoot.xml b/doc/user/troubleshoot.xml
index beea8c9..7049deb 100644
--- a/doc/user/troubleshoot.xml
+++ b/doc/user/troubleshoot.xml
@@ -442,6 +442,19 @@ inc.h
 
     <para>
 
+    By default &SCons; uses "ASCII art" to draw the tree. It is
+    possible to use line-drawing characters (Unicode calls these
+    Box Drawing) to make a nicer display. To do this, add the
+    <option>linedraw</option> qualifier:
+
+    </para>
+
+    <scons_output example="troubleshoot_tree1" suffix="2">
+      <scons_output_command>scons -Q --tree=all,linedraw</scons_output_command>
+    </scons_output>
+
+    <para>
+
     The <option>--tree</option> option only prints
     the dependency graph for the specified targets
     (or the default target(s) if none are specified on the command line).
@@ -452,7 +465,7 @@ inc.h
 
     </para>
 
-    <scons_output example="troubleshoot_tree1" suffix="2">
+    <scons_output example="troubleshoot_tree1" suffix="3">
       <scons_output_command>scons -Q --tree=all f2.o</scons_output_command>
     </scons_output>
 
@@ -468,7 +481,7 @@ inc.h
 
     </para>
 
-    <scons_output example="troubleshoot_tree1" suffix="3">
+    <scons_output example="troubleshoot_tree1" suffix="4">
       <scons_output_command>scons -Q --tree=all f1.o f3.o</scons_output_command>
     </scons_output>
 
@@ -480,7 +493,7 @@ inc.h
 
     </para>
 
-    <scons_output example="troubleshoot_tree1" suffix="4">
+    <scons_output example="troubleshoot_tree1" suffix="5">
       <scons_output_command>scons -Q --tree=status</scons_output_command>
     </scons_output>
 
@@ -498,7 +511,7 @@ inc.h
 
     </para>
 
-    <scons_output example="troubleshoot_tree1" suffix="5">
+    <scons_output example="troubleshoot_tree1" suffix="6">
       <scons_output_command>scons -Q --tree=derived</scons_output_command>
     </scons_output>
 
@@ -509,7 +522,7 @@ inc.h
 
     </para>
 
-    <scons_output example="troubleshoot_tree1" suffix="6">
+    <scons_output example="troubleshoot_tree1" suffix="7">
       <scons_output_command>scons -Q --tree=derived,status</scons_output_command>
     </scons_output>
 
diff --git a/src/engine/SCons/Util.py b/src/engine/SCons/Util.py
index e55ccb4..767b3f9 100644
--- a/src/engine/SCons/Util.py
+++ b/src/engine/SCons/Util.py
@@ -267,6 +267,7 @@ def print_tree(root, child_func, prune=0, showtags=0, margin=[0], visited=None,
         - `showtags`   - print status information to the left of each node line
         - `margin`     - the format of the left margin to use for children of root. 1 results in a pipe, and 0 results in no pipe.
         - `visited`    - a dictionary of visited nodes in the current branch if not prune, or in the whole tree if prune.
+        - `singleLineDraw` - use line-drawing characters rather than ASCII.
     """
 
     rname = str(root)
@@ -301,7 +302,7 @@ def print_tree(root, child_func, prune=0, showtags=0, margin=[0], visited=None,
                 [0, 2][IDX(root.has_builder())]
             ],
             ' S'[IDX(root.side_effect)],
-			' P'[IDX(root.precious)],
+            ' P'[IDX(root.precious)],
             ' A'[IDX(root.always_build)],
             ' C'[IDX(root.is_up_to_date())],
             ' N'[IDX(root.noclean)],
@@ -322,21 +323,32 @@ def print_tree(root, child_func, prune=0, showtags=0, margin=[0], visited=None,
 
     children = child_func(root)
 
+
     cross = "+-"
     if singleLineDraw:
-        cross = "├─"  # sign used to point to the leaf.
+        # unicode line drawing chars:
+        box_horiz = chr(0x2500) # '─'
+        box_vert = chr(0x2510) # '│'
+        box_up_right = chr(0x2514) # '└'
+        box_down_right = chr(0x250c) # '┌'
+        box_down_left = chr(0x2510)  # '┐'
+        box_up_left = chr(0x2518) # '┘'
+        box_vert_right = chr(0x251c) # '├'
+        box_horiz_down = chr(0x252c) # '┬'
+
+        cross = box_vert_right + box_horiz   # sign used to point to the leaf.
         # check if this is the last leaf of the branch
         if lastChild:
             #if this if the last leaf, then terminate:
-            cross = "└─" # sign for the last leaf
+            cross = box_up_right + box_horiz  # sign for the last leaf
 
         # if this branch has children then split it
-        if len(children)>0:
+        if children:
             # if it's a leaf:
             if prune and rname in visited and children:
-                cross += "─"
+                cross += box_horiz
             else:
-                cross += "┬"
+                cross += box_horiz_down
 
     if prune and rname in visited and children:
         sys.stdout.write(''.join(tags + margins + [cross,'[', rname, ']']) + '\n')
diff --git a/test/option--tree.py b/test/option--tree.py
index 0beec7f..290f1d4 100644
--- a/test/option--tree.py
+++ b/test/option--tree.py
@@ -47,60 +47,42 @@ SCons Error: `foofoo' is not a valid --tree option type, try:
 
 
 # Test that unicode characters can be printed (escaped) with the --tree option
-test.write('SConstruct',
-           """
+test.write('SConstruct', """\
 env = Environment()
 env.Tool("textfile")
-try:
-    # Python 2
-    write = unichr(0xe7).encode('utf-8')
-except NameError:
-    # Python 3
-    # str is utf-8 by default
-    write = chr(0xe7)
-env.Textfile("Foo", write)
+name = "français"
+env.Textfile("Foo", name)
 """)
 
-if sys.version_info.major < 3:
-    py23_char = unichr(0xe7).encode('utf-8')
-else:
-    py23_char = chr(0xe7)
+uchar = chr(0xe7)
 
 expected = """Creating 'Foo.txt'
 +-.
   +-Foo.txt
-  | +-""" + py23_char + """
+  | +-fran%sais
   +-SConstruct
-"""
+""" % uchar
 
-test.run(arguments='-Q --tree=all',
-         stdout=expected,
-         status=0)
+test.run(arguments='-Q --tree=all', stdout=expected, status=0)
 
-#Tests the new command line option "linedraw"
-test.write('SConstruct',
-           """
+# Test the "linedraw" option: same basic test as previous.
+# With "--tree=linedraw" must default to "all", and use line-drawing chars.
+test.write('SConstruct', """\
 env = Environment()
 env.Tool("textfile")
-# Python 3
-# str is utf-8 by default
-write = chr(0xe7)
-env.Textfile("LineDraw", write)
+name = "français"
+env.Textfile("LineDraw", name)
 """)
 
-py23_char = chr(0xe7)
-
 expected = """Creating 'LineDraw.txt'
 └─┬.
   ├─┬LineDraw.txt
-  │ └─""" + py23_char + """
+  │ └─fran%sais
   └─SConstruct
-"""
+""" % uchar
 
 
-test.run(arguments='-Q --tree=linedraw',
-        stdout=expected,
-        status=0)
+test.run(arguments='-Q --tree=linedraw', stdout=expected, status=0)
 
 test.pass_test()