Show better error location for missing CSS definition semicolon.

Fixes #726

spec/errors/css_definition_expected_semicolon_2

@@ -0,0 +1,18 @@
+component Main {
+  style root {
+    background: red
+  }
+}
+--------------------------------------------------------------------------------
+░ ERROR (CSS_DEFINITION_EXPECTED_SEMICOLON) ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
+
+I was expecting the semicolon of a CSS definition but I found "a space" instead:
+
+   ┌ errors/css_definition_expected_semicolon_2:3:19
+   ├────────────────────────────────────────────────
+  1│ component Main {
+  2│   style root {
+  3│     background: red
+   │                    ⌃⌃⌃⌃
+  4│   }
+  5│ }

src/errorable.cr

@@ -23,7 +23,8 @@ module Mint
   class Error < Exception
     # Anything that can be a snippet.
     alias SnippetTarget = TypeChecker::Checkable | SnippetData |
-                          Ast::Node | Parser | String
+                          Ast::Node | Parser | String |
+                          Tuple(Parser, Parser::Location)
 
     alias Element = Text | Bold | Code
 
@@ -80,6 +81,18 @@ module Mint
     def snippet(value : SnippetTarget)
       target =
         case value
+        in Tuple(Parser, Parser::Location)
+          parser, position =
+            value
+
+          min =
+            parser.input[position.offset]? == '\0' ? 0 : 1
+
+          SnippetData.new(
+            to: position.offset + [min, parser.word(position).to_s.size].max,
+            filename: parser.file.relative_path,
+            input: parser.file.contents,
+            from: position.offset)
         in Parser
           min =
             value.char == '\0' ? 0 : 1

src/parser.cr

@@ -181,6 +181,18 @@ module Mint
       word
     end
 
+    # Returns the word (non whitespace sequence) a the position.
+    def word(position : Location)
+      current = position.offset
+      word = ""
+
+      while (char = input[current]?) && !char.ascii_whitespace?
+        word += char
+      end
+
+      word
+    end
+
     # Returns whether or not the word is at the current position.
     def word?(word) : Bool
       word.chars.each_with_index.all? do |char, i|
@@ -411,5 +423,31 @@ module Mint
         end
       end
     end
+
+    # Returns the last non whitespace position.
+    def last_non_whitespace_position
+      position, line, column =
+        @position.to_tuple
+
+      while input[position - 1]?.try(&.ascii_whitespace?)
+        case previous_char
+        when '\n'
+          current = position - 2
+          column = 0_i64
+          line -= 1
+
+          while input[current]? && (input[current] != '\n')
+            current -= 1
+            column += 1
+          end
+        else
+          column -= 1
+        end
+
+        position -= 1
+      end
+
+      Location.new(offset: position, line: line, column: column)
+    end
   end
 end

src/parsers/css_definition.cr

@@ -9,7 +9,7 @@ module Mint
 
         value =
           many(parse_whitespace: false) {
-            string_literal || interpolation || raw { char.in_set?("^;{\0\"") }
+            string_literal || interpolation || raw { char.in_set?("^;}{\0\"") }
           }.map do |item|
             if item.is_a?(Ast::StringLiteral) && (raw = static_value(item))
               %("#{raw}")
@@ -19,8 +19,11 @@ module Mint
           end
 
         next error :css_definition_expected_semicolon do
-          expected "the semicolon of a CSS definition", word
-          snippet self
+          position =
+            last_non_whitespace_position
+
+          expected "the semicolon of a CSS definition", word(position)
+          snippet({self, position})
         end unless char! ';'
 
         Ast::CssDefinition.new(

src/utils/terminal_snippet.cr

@@ -165,7 +165,8 @@ module Mint
               line.highlight(from, to)
 
             "#{gutter} #{a}\n#{" " * gutter_width}│ #{b}"
-          elsif from == input.size && line.offset + line.contents.size == from
+          elsif (from == input.size && line.offset + line.contents.size == from) ||
+                (line.offset + line.contents.size == (to - 1))
             "#{gutter} #{line.contents}\n#{" " * gutter_width}│ #{" " * line.contents.size}⌃⌃⌃⌃"
           end || "#{gutter} #{line.contents}"
         end