generate-cmdlist: parse common group commands

Parse the group block to create the array of group descriptions:

static char *common_cmd_groups[] = {
    N_("starting a working area"),
    N_("working on the current change"),
    N_("working with others"),
    N_("examining the history and state"),
    N_("growing, marking and tweaking your history"),
};

then map each element of common_cmds[] to a group via its index:

static struct cmdname_help common_cmds[] = {
    {"add", N_("Add file contents to the index"), 1},
    {"branch", N_("List, create, or delete branches"), 4},
    {"checkout", N_("Checkout a branch or paths to the ..."), 4},
    {"clone", N_("Clone a repository into a new directory"), 0},
    {"commit", N_("Record changes to the repository"), 4},
    ...
};

so that 'git help' can print those commands grouped by theme.

Only commands tagged with an attribute from the group block are emitted to
common_cmds[].

[commit message by Sébastien Guimmara <sebastien.guimmara@gmail.com>]

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Sébastien Guimmara <sebastien.guimmara@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -1687,10 +1687,10 @@ $(BUILT_INS): git$X
 	ln -s $< $@ 2>/dev/null || \
 	cp $< $@
 
-common-cmds.h: ./generate-cmdlist.sh command-list.txt
+common-cmds.h: generate-cmdlist.perl command-list.txt
 
 common-cmds.h: $(wildcard Documentation/git-*.txt)
-	$(QUIET_GEN)./generate-cmdlist.sh > $@+ && mv $@+ $@
+	$(QUIET_GEN)$(PERL_PATH) generate-cmdlist.perl command-list.txt > $@+ && mv $@+ $@
 
 SCRIPT_DEFINES = $(SHELL_PATH_SQ):$(DIFF_SQ):$(GIT_VERSION):\
 	$(localedir_SQ):$(NO_CURL):$(USE_GETTEXT_SCHEME):$(SANE_TOOL_PATH_SQ):\

generate-cmdlist.perl

@@ -0,0 +1,50 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+
+print <<"EOT";
+/* Automatically generated by $0 */
+
+struct cmdname_help {
+	char name[16];
+	char help[80];
+	unsigned char group;
+};
+
+static char *common_cmd_groups[] = {
+EOT
+
+my $n = 0;
+my %grp;
+while (<>) {
+	last if /^### command list/;
+	next if (1../^### common groups/) || /^#/ || /^\s*$/;
+	chop;
+	my ($k, $v) = split ' ', $_, 2;
+	$grp{$k} = $n++;
+	print "\tN_(\"$v\"),\n";
+}
+
+print "};\n\nstatic struct cmdname_help common_cmds[] = {\n";
+
+while (<>) {
+	next if /^#/ || /^\s*$/;
+	my @tags = split;
+	my $cmd = shift @tags;
+	for my $t (@tags) {
+		if (exists $grp{$t}) {
+			my $s;
+			open my $f, '<', "Documentation/$cmd.txt" or die;
+			while (<$f>) {
+				($s) = /^$cmd - (.+)$/;
+				last if $s;
+			}
+			close $f;
+			$cmd =~ s/^git-//;
+			print "\t{\"$cmd\", N_(\"$s\"), $grp{$t}},\n";
+			last;
+		}
+	}
+}
+
+print "};\n";