From 550b972c7865560dab6b71186dbb4855627f28ed Mon Sep 17 00:00:00 2001
From: Vovanium <vovanium@disroot.org>
Date: Mon, 24 Apr 2023 22:40:26 +0300
Subject: [PATCH] * single replace and its example

---
 alire.toml                                    |  2 +-
 gpr/examples.gpr                              |  2 +
 source/examples/replace.adb                   | 46 +++++++++++++++++++
 .../encodings-generic_single_replace.adb      | 18 ++++++--
 4 files changed, 64 insertions(+), 4 deletions(-)
 create mode 100644 source/examples/replace.adb

diff --git a/alire.toml b/alire.toml
index 88405b8..6e0dbd2 100644
--- a/alire.toml
+++ b/alire.toml
@@ -9,4 +9,4 @@ maintainers-logins = ["vovanium"]
 project-files = ["gpr/encodings.gpr", "gpr/test.gpr", "gpr/examples.gpr"]
 
 [[depends-on]]
-aunit = "^23.0.0"
+aunit = ">=22.0.0"
diff --git a/gpr/examples.gpr b/gpr/examples.gpr
index 6f95804..27d0179 100644
--- a/gpr/examples.gpr
+++ b/gpr/examples.gpr
@@ -7,4 +7,6 @@ project Examples extends "common" is
 	package Builder is
 		For Default_Switches("Ada") use Common.Default_Switches;
 	end Builder;
+
+	for Main use ("add_cr", "strip_cr", "replace");
 end Examples;
\ No newline at end of file
diff --git a/source/examples/replace.adb b/source/examples/replace.adb
new file mode 100644
index 0000000..4af2fda
--- /dev/null
+++ b/source/examples/replace.adb
@@ -0,0 +1,46 @@
+--
+-- Program reads standard input, replaces string in first parameter
+-- with one in second, then writes to standard output
+--
+
+with Ada.Streams, Ada.Text_IO, Ada.Text_IO.Text_Streams;
+use  Ada.Streams, Ada.Text_IO, Ada.Text_IO.Text_Streams;
+with Ada.Command_Line;
+use  Ada.Command_Line;
+with Encodings.Generic_Single_Replace;
+with Encodings.Utility, Encodings.Converters;
+use  Encodings.Utility, Encodings.Converters;
+
+procedure Replace is
+
+	Input_Stream    : Stream_Access := Stream (Standard_Input);
+	Output_Stream   : Stream_Access := Stream (Standard_Output);
+	Input_Buffer    : String (1 .. 100);
+	Output_Buffer   : String (1 .. 100);
+	Input_Last,
+	Input_Read_Last : Natural;
+	Output_Last     : Natural;
+begin
+	if Argument_Count < 2 then
+		return;
+	end if;
+	declare
+		package Coders is new Encodings.Generic_Single_Replace (
+			Character_Type => Character,
+			String_Type => String,
+			Original => Argument (1),
+			Replacement => Argument (2),
+			Converter_Base  => Encodings.Converters.Character_To_Character);
+		Coder : Coders.Converter;
+	begin
+		while not End_Of_File (Standard_Input) loop
+			Read_String (Input_Stream.all, Input_Buffer, Input_Read_Last);
+			Input_Last := Input_Buffer'First - 1;
+			while Input_Last < Input_Read_Last loop
+				Coder.Process (Input_Buffer (Input_Last + 1 .. Input_Read_Last),
+					Input_Last, Output_Buffer, Output_Last);
+				String'Write (Output_Stream, Output_Buffer (Output_Buffer'First .. Output_Last));
+			end loop;
+		end loop;
+	end;
+end Replace;
diff --git a/source/library/encodings-generic_single_replace.adb b/source/library/encodings-generic_single_replace.adb
index a20ff2c..444442c 100644
--- a/source/library/encodings-generic_single_replace.adb
+++ b/source/library/encodings-generic_single_replace.adb
@@ -32,8 +32,17 @@ package body Encodings.Generic_Single_Replace is
 				C := Source (Source_Cursor);
 				if C = Original (This.SI) then -- original match
 					if This.SI = Original'Last then -- full string matched
-						This.TI := Replacement'First - 1;
-						This.S := Output_Replacement;
+						case Replacement'Length is
+						when 0 =>
+							This.SI := Original'First;
+						when 1 =>
+							Put (Replacement (Replacement'First));
+							This.SI := Original'First;
+						when others =>
+							Put (Replacement (Replacement'First));
+							This.TI := Replacement'First;
+							This.S := Output_Replacement;
+						end case;
 					else
 						This.SI := This.SI + 1;
 					end if;
@@ -41,7 +50,8 @@ package body Encodings.Generic_Single_Replace is
 					if This.SI = Original'First then -- no matched prefix
 						Put (C);
 					else
-						This.TI := Original'First - 1;
+						This.TI := Original'First;
+						Put (Original (Original'First));
 						This.C := C;
 						This.S := Output_Original;
 					end if;
@@ -50,6 +60,7 @@ package body Encodings.Generic_Single_Replace is
 				This.TI := This.TI + 1;
 				if This.TI = This.SI then -- whole matched part already written
 					Put (This.C);
+					This.SI := Original'First;
 					This.S := Initial;
 				else
 					Put (Original (This.TI));
@@ -58,6 +69,7 @@ package body Encodings.Generic_Single_Replace is
 				This.TI := This.TI + 1;
 				Put (Replacement (This.TI));
 				if This.TI = Replacement'Last then
+					This.SI := Original'First;
 					This.S := Initial;
 				end if;
 			end case;