From 331d918190cc1b722e1469dd29bb94142bc4e14b Mon Sep 17 00:00:00 2001
From: Karchnu <karchnu@karchnu.fr>
Date: Mon, 30 Nov 2020 04:55:15 +0100
Subject: [PATCH] string-keys-to-int: converting string keys into integers.

---
 README.md                 | 10 +++++
 shard.yml                 |  2 +
 src/string-keys-to-int.cr | 89 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+)
 create mode 100644 src/string-keys-to-int.cr

diff --git a/README.md b/README.md
index 76f221d..3029f65 100644
--- a/README.md
+++ b/README.md
@@ -25,3 +25,13 @@ json-to-cbor < file.json > file.cbor
 hs < file.cbor
 ```
 
+# string-keys-to-int usage
+
+JSON format has a limitation on the type of hash keys: it has to be a string.
+CBOR doesn't come with such limitation.
+`string-keys-to-int` automatically converts string keys into integers, whenever all the keys in a hash can be converted.
+
+```sh
+string-keys-to-int < file.cbor
+```
+
diff --git a/shard.yml b/shard.yml
index fe1de54..8293371 100644
--- a/shard.yml
+++ b/shard.yml
@@ -14,6 +14,8 @@ targets:
     main: src/json-to-cbor.cr
   hs:
     main: src/hs.cr
+  string-keys-to-int:
+    main: src/string-keys-to-int.cr
   bm-json-vs-cbor:
     main: tests/json-vs-cbor.cr
 
diff --git a/src/string-keys-to-int.cr b/src/string-keys-to-int.cr
new file mode 100644
index 0000000..8dddadb
--- /dev/null
+++ b/src/string-keys-to-int.cr
@@ -0,0 +1,89 @@
+require "cbor"
+require "option_parser"
+
+class Context
+	class_property debug = false
+end
+
+OptionParser.parse do |parser|
+	parser.banner = "usage: string-keys-to-int < file.cbor"
+
+	parser.on "-d", "--debug",
+		"Debug: print keys to convert, input and output data." do
+		Context.debug = true
+	end
+
+	parser.on "-h", "--help", "Displays this help and exits." do
+		puts parser
+		exit 0
+	end
+end
+
+def are_hash_keys_all_int?(data)
+	case d = data
+	when Hash
+		keys = d.keys
+		if keys.all? {|v| v.is_a?(String) }
+		  keys.all?  {|v| v.as(String).to_i64 rescue false }
+		else
+		  false
+		end
+	else
+		false
+	end
+end
+
+def change(data)
+	# 1. change keys
+	if are_hash_keys_all_int? data 
+		if Context.debug
+			puts "keys to convert: #{data.as(Hash).keys}"
+		end
+
+		# Do something
+		case d = data
+		when Hash
+			keys = d.keys
+			keys.each do |k|
+				d[k.as(String).to_i32] = d[k]
+				d.delete k
+			end
+		end
+	end
+
+	# 2. dig
+	case d = data
+	when Hash
+		keys = d.keys
+		keys.each do |k|
+			change d[k]
+		end
+	end
+rescue e
+	STDERR.puts "something went wrong: #{e}"
+end
+
+buffer = Bytes.new 1_000_000 # 1 MB
+
+until STDIN.read(buffer) == 0
+	decoder = CBOR::Decoder.new(buffer)
+	while data = decoder.read_value
+		break if data == 0
+
+		if Context.debug
+			puts "input data:"
+			pp data
+		end
+
+		change data
+
+		if Context.debug
+			puts "output data:"
+			pp data
+		else
+			STDOUT.write data.to_cbor
+			STDOUT.flush
+		end
+	end
+	buffer = Bytes.new 1_000_000 # 1 MB
+end