Add type restrictions to CSV (#15695)

Author: Vici37

src/csv.cr

@@ -113,7 +113,7 @@ class CSV
   # rows.next # => ["one", "two"]
   # rows.next # => ["three"]
   # ```
-  def self.each_row(string_or_io : String | IO, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
+  def self.each_row(string_or_io : String | IO, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR) : Iterator(Array(String))
     Parser.new(string_or_io, separator, quote_char).each_row
   end
 
@@ -174,7 +174,7 @@ class CSV
   # Headers are always stripped.
   #
   # See `CSV.parse` about the *separator* and *quote_char* arguments.
-  def initialize(string_or_io : String | IO, headers = false, @strip = false, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
+  def initialize(string_or_io : String | IO, headers : Bool = false, @strip : Bool = false, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
     @parser = Parser.new(string_or_io, separator, quote_char)
     if headers
       headers = @parser.next_row || ([] of String)

src/csv/builder.cr

@@ -81,7 +81,7 @@ class CSV::Builder
   end
 
   # :nodoc:
-  def quote_cell(value : String)
+  def quote_cell(value : String) : Nil
     append_cell do
       @io << @quote_char
       value.each_char do |char|

src/csv/error.cr

@@ -10,7 +10,7 @@ class CSV
     getter line_number : Int32
     getter column_number : Int32
 
-    def initialize(message, @line_number, @column_number)
+    def initialize(message : String, @line_number : Int32, @column_number : Int32)
       super("#{message} at line #{@line_number}, column #{@column_number}")
     end
   end

src/csv/lexer.cr

@@ -15,12 +15,12 @@ require "csv"
 # ```
 abstract class CSV::Lexer
   # Creates a CSV lexer from a `String`.
-  def self.new(string : String, separator = DEFAULT_SEPARATOR, quote_char = DEFAULT_QUOTE_CHAR)
+  def self.new(string : String, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR) : self
     StringBased.new(string, separator, quote_char)
   end
 
   # Creates a CSV lexer from an `IO`.
-  def self.new(io : IO, separator = DEFAULT_SEPARATOR, quote_char = DEFAULT_QUOTE_CHAR)
+  def self.new(io : IO, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR) : self
     IOBased.new(io, separator, quote_char)
   end
 

src/csv/lexer/io_based.cr

@@ -2,7 +2,7 @@ require "csv"
 
 # :nodoc:
 class CSV::Lexer::IOBased < CSV::Lexer
-  def initialize(@io : IO, separator = DEFAULT_SEPARATOR, quote_char = DEFAULT_QUOTE_CHAR)
+  def initialize(@io : IO, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
     super(separator, quote_char)
     @current_char = @io.read_char || '\0'
   end

src/csv/lexer/string_based.cr

@@ -2,7 +2,7 @@ require "csv"
 
 # :nodoc:
 class CSV::Lexer::StringBased < CSV::Lexer
-  def initialize(string, separator = DEFAULT_SEPARATOR, quote_char = DEFAULT_QUOTE_CHAR)
+  def initialize(string : String, separator : Char = DEFAULT_SEPARATOR, quote_char : Char = DEFAULT_QUOTE_CHAR)
     super(separator, quote_char)
     @reader = Char::Reader.new(string)
     if @reader.current_char == '\n'

src/csv/parser.cr

@@ -27,7 +27,7 @@ class CSV::Parser
   end
 
   # Returns an `Iterator` of `Array(String)` for the remaining rows.
-  def each_row
+  def each_row : Iterator(Array(String))
     RowIterator.new(self)
   end