From 0778c66917daba1a0dc948eacdf86578ec4dd2be Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Mon, 26 Aug 2024 01:55:02 +0200
Subject: User may now ask for multiple standards/tags from the CLI utility

---
 headers.lua          |  6 +++---
 headers/parser.lua   | 35 ++++++++++++++++++++++-------------
 spec/parser_spec.lua | 17 +++++++++++++----
 3 files changed, 38 insertions(+), 20 deletions(-)

diff --git a/headers.lua b/headers.lua
index 680142d..290aca3 100755
--- a/headers.lua
+++ b/headers.lua
@@ -1,8 +1,8 @@
 #!/usr/bin/env lua
 local args = require "pl.lapp" [[
 Prints list of headers from a standard or available standards
-	-d  (string default 'db/')      Directory where definitions are placed
-	<selection>  (optional string)  Standard to display headers for
+	-d  (string default 'db/')  Directory where definitions are placed
+	<selection...>  (optional string)  Standard to display the headers for
 ]]
 local dir = require "pl.dir"
 local parser = require "headers.parser".new()
@@ -13,7 +13,7 @@ for _, filename in pairs(definitions) do
 	handle:close()
 	parser:parse(data)
 end
-if args.selection then
+if #args.selection > 0 then
 	local headers = parser:get_headers(args.selection)
 	if not headers then
 		os.exit(1)
diff --git a/headers/parser.lua b/headers/parser.lua
index 45dc322..33b212b 100644
--- a/headers/parser.lua
+++ b/headers/parser.lua
@@ -1,3 +1,4 @@
+local seq = require "pl.seq"
 local tablex = require "pl.tablex"
 local definition = require "headers.definition"
 local multiset = require "headers.multiset"
@@ -104,25 +105,33 @@ function parser:parse (input)
 end
 
 
+local
+function less_than (lhs, rhs)
+	return lhs < rhs
+end
+
+
 function parser:get_tags ()
-	local names = {}
-	for _, tag in tablex.sortv(self.tags, function (lhs, rhs) return tostring(lhs) < tostring(rhs) end) do
-		table.insert(names, tostring(tag))
-	end
-	return names
+	return seq.copy(seq.sort(seq.map(tostring, self.tags), less_than))
 end
 
 
-function parser:get_headers (tag)
-	local found = self:get_tag(tag)
-	if not found then
-		return nil
+function parser:get_headers (tags)
+	local all = {}
+	for _, tag in pairs(tags) do
+		local found = self:get_tag(tag)
+		if found then
+			local headers = {}
+			for header in found.headers:all() do
+				headers[header] = true
+			end
+			tablex.update(all, headers)
+		end
 	end
-	local names = {}
-	for header in found.headers:all() do
-		table.insert(names, header)
+	if tablex.size(all) > 0 then
+		return seq.copy(seq.sort(seq.keys(all), less_than))
 	end
-	return names
+	return nil
 end
 
 
diff --git a/spec/parser_spec.lua b/spec/parser_spec.lua
index f20ae0f..b2d91fc 100644
--- a/spec/parser_spec.lua
+++ b/spec/parser_spec.lua
@@ -55,12 +55,12 @@ describe("Headers", function()
 
 	it("are not available if never assigned", function()
 		headers:parse [[]]
-		assert.is_nil(headers:get_headers("Example"))
+		assert.is_nil(headers:get_headers{"Example"})
 	end)
 
 	it("can be assigned to a tag", function()
 		headers:parse [[headers "Example" {"example.h"}]]
-		assert.are.same({"example.h"}, headers:get_headers("Example"))
+		assert.are.same({"example.h"}, headers:get_headers{"Example"})
 	end)
 
 	it("can be included from another tag", function()
@@ -68,7 +68,7 @@ describe("Headers", function()
 			headers "Parent" {"example.h"}
 			headers "Derived" {include "Parent"}
 		]]
-		assert.are.same({"example.h"}, headers:get_headers("Derived"))
+		assert.are.same({"example.h"}, headers:get_headers{"Derived"})
 	end)
 
 	it("can be removed after including from another tag", function()
@@ -76,6 +76,15 @@ describe("Headers", function()
 			headers "Parent" {"example.h", "removed.h"}
 			headers "Derived" {include "Parent", remove "removed.h"}
 		]]
-		assert.are.same({"example.h"}, headers:get_headers("Derived"))
+		assert.are.same({"example.h"}, headers:get_headers{"Derived"})
+	end)
+
+	it("can be retrieved from number of tags", function()
+		headers:parse [[
+			headers "First" {"first.h"}
+			headers "Second" {"second.h"}
+		]]
+		assert.are.same({"first.h"}, headers:get_headers{"First"})
+		assert.are.same({"first.h", "second.h"}, headers:get_headers{"First", "Second"})
 	end)
 end)
-- 
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