Use more natural way to define error with custom loc

spec/ameba/formatter/flycheck_formatter_spec.cr

@@ -18,7 +18,7 @@ module Ameba::Formatter
     context "when problems found" do
       it "reports an error" do
         s = Source.new "a = 1", "source.cr"
-        s.error DummyRule.new, s.location(1, 2), "message"
+        s.error DummyRule.new, 1, 2, "message"
         subject = flycheck
         subject.source_finished s
         subject.output.to_s.should eq "source.cr:1:2: E: message\n"
@@ -26,7 +26,7 @@ module Ameba::Formatter
 
       it "properly reports multi-line message" do
         s = Source.new "a = 1", "source.cr"
-        s.error DummyRule.new, s.location(1, 2), "multi\nline"
+        s.error DummyRule.new, 1, 2, "multi\nline"
         subject = flycheck
         subject.source_finished s
         subject.output.to_s.should eq "source.cr:1:2: E: multi line\n"

spec/ameba/formatter/todo_formatter_spec.cr

@@ -6,7 +6,7 @@ module Ameba
     formatter = Formatter::TODOFormatter.new IO::Memory.new, file
 
     s = Source.new "a = 1", "source.cr"
-    s.error DummyRule.new, s.location(1, 2), "message"
+    s.error DummyRule.new, 1, 2, "message"
 
     formatter.finished [s]
     file.to_s
@@ -57,7 +57,7 @@ module Ameba
           formatter = Formatter::TODOFormatter.new IO::Memory.new, file
 
           s = Source.new "def invalid_syntax"
-          s.error Rule::Syntax.new, s.location(1, 2), "message"
+          s.error Rule::Syntax.new, 1, 2, "message"
 
           formatter.finished [s]
           content = file.to_s

spec/ameba/source_spec.cr

@@ -14,7 +14,7 @@ module Ameba
     describe "#error" do
       it "adds and error" do
         s = Source.new "", "source.cr"
-        s.error(DummyRule.new, s.location(23, 2), "Error!")
+        s.error(DummyRule.new, 23, 2, "Error!")
         s.should_not be_valid
 
         error = s.errors.first

spec/spec_helper.cr

@@ -13,8 +13,7 @@ module Ameba
 
   struct ErrorRule < Rule::Base
     def test(source)
-      source.error self, source.location(1, 1),
+      source.error self, 1, 1, "This rule always adds an error"
-        "This rule always adds an error"
     end
   end
 

src/ameba/rule/line_length.cr

@@ -20,8 +20,7 @@ module Ameba::Rule
       source.lines.each_with_index do |line, index|
         next unless line.size > max_length
 
-        source.error self, source.location(index + 1, line.size),
+        source.error self, index + 1, line.size, "Line too long"
-          "Line too long"
       end
     end
   end

src/ameba/rule/syntax.cr

@@ -23,8 +23,7 @@ module Ameba::Rule
     def test(source)
       source.ast
     rescue e : Crystal::SyntaxException
-      location = source.location(e.line_number, e.column_number)
+      source.error self, e.line_number, e.column_number, e.message.to_s
-      source.error self, location, e.message.to_s
     end
   end
 end

src/ameba/rule/trailing_blank_lines.cr

@@ -15,7 +15,7 @@ module Ameba::Rule
 
     def test(source)
       if source.lines.size > 1 && source.lines[-2, 2].join.strip.empty?
-        source.error self, source.location(source.lines.size, 1),
+        source.error self, source.lines.size, 1,
           "Blank lines detected at the end of the file"
       end
     end

src/ameba/rule/trailing_whitespace.cr

@@ -16,8 +16,7 @@ module Ameba::Rule
     def test(source)
       source.lines.each_with_index do |line, index|
         next unless line =~ /\s$/
-        source.error self, source.location(index + 1, line.size),
+        source.error self, index + 1, line.size, "Trailing whitespace detected"
-          "Trailing whitespace detected"
       end
     end
   end

src/ameba/source.cr

@@ -36,7 +36,7 @@ module Ameba
     def initialize(@code : String, @path = "")
     end
 
-    # Add new error to the list of errors.
+    # Adds new error to the list of errors.
     #
     # ```
     # source.error rule, location, "Line too long"
@@ -46,6 +46,17 @@ module Ameba
       errors << Error.new rule, location, message
     end
 
+    # Adds new error to the list of errors using line and column number.
+    #
+    # ```
+    # source.error rule, line_number, column_number, "Bad code"
+    # ```
+    #
+    def error(rule : Rule::Base, l : Int32, c : Int32, message : String)
+      location = Crystal::Location.new path, l, c
+      error rule, location, message
+    end
+
     # Indicates whether source is valid or not.
     # Returns true if the list or errors empty, false otherwise.
     #
@@ -89,18 +100,6 @@ module Ameba
                        .parse
     end
 
-    # Returns a new instance of the `Crystal::Location` in current
-    # source based on the line number `l` and column number `c`.
-    #
-    # ```
-    # s = Ameba::Source.new code, path
-    # s.location(3, 76)
-    # ```
-    #
-    def location(l, c)
-      Crystal::Location.new path, l, c
-    end
-
     def fullpath
       @fullpath ||= File.expand_path @path
     end