Adds support for default error reporting (#83)

- By raising SyntaxTree::Parser::ParseError with default arguments
  it returns much nicer error messages.

lib/syntax_tree/erb/parser.rb

@@ -5,14 +5,12 @@ module ERB
  class Parser
  # This is the parent class of any kind of errors that will be raised by
  # the parser.
- class ParseError < StandardError
- end
 
  # This error occurs when a certain token is expected in a certain place
  # but is not found. Sometimes this is handled internally because some
  # elements are optional. Other times it is not and it is raised to end the
  # parsing process.
- class MissingTokenError < ParseError
+ class MissingTokenError < SyntaxTree::Parser::ParseError
  end
 
  attr_reader :source, :tokens
@@ -52,7 +50,13 @@ def parse_any_tag
 
  if tag.is_a?(Doctype)
  if @found_doctype
- raise(ParseError, "Only one doctype element is allowed")
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Only one doctype element is allowed",
+ tag.location.start_line,
+ 0
+ )
+ )
  else
  @found_doctype = true
  end
@@ -123,8 +127,13 @@ def make_tokens
  # abc
  enum.yield :text, $&, index, line
  else
- raise ParseError,
- "Unexpected character at #{index}: #{source[index]}"
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Unexpected character at #{index}: #{source[index]}",
+ line,
+ 0
+ )
+ )
  end
  in :erb_start
  case source[index..]
@@ -207,8 +216,13 @@ def make_tokens
  # abc
  enum.yield :text, $&, index, line
  else
- raise ParseError,
- "Unexpected character in string at #{index}: #{source[index]}"
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Unexpected character in string at #{index}: #{source[index]}",
+ line,
+ 0
+ )
+ )
  end
  in :string_double_quote
  case source[index..]
@@ -230,8 +244,13 @@ def make_tokens
  # abc
  enum.yield :text, $&, index, line
  else
- raise ParseError,
- "Unexpected character in string at #{index}: #{source[index]}"
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Unexpected character in string at #{index}: #{source[index]}",
+ line,
+ 0
+ )
+ )
  end
  in :inside
  case source[index..]
@@ -284,8 +303,13 @@ def make_tokens
  enum.yield :string_open_single_quote, $&, index, line
  state << :string_single_quote
  else
- raise ParseError,
- "Unexpected character at #{index}: #{source[index]}"
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Unexpected character at #{index}: #{source[index]}",
+ line,
+ 0
+ )
+ )
  end
  end
 
@@ -304,7 +328,13 @@ def consume(expected)
  type, value, index, line = tokens.peek
 
  if expected != type
- raise MissingTokenError, "expected #{expected} got #{type}"
+ raise(
+ MissingTokenError.new(
+ "expected #{expected} got #{type}",
+ line,
+ index
+ )
+ )
  end
 
  tokens.next
@@ -335,7 +365,9 @@ def maybe
  # Otherwise we'll return the value returned by the block.
  def atleast
  result = yield
- raise MissingTokenError if result.nil?
+ if result.nil?
+ raise(MissingTokenError.new("No matching token", nil, nil))
+ end
  result
  end
 
@@ -372,7 +404,13 @@ def parse_html_opening_tag
  name = consume(:name)
 
  if name.value =~ /\A[@:#]/
- raise ParseError, "Invalid html-tag name #{name}"
+ raise(
+ SyntaxTree::Parser::ParseError.new(
+ "Invalid html-tag name #{name}",
+ name.location.start_line,
+ 0
+ )
+ )
  end
 
  attributes =
@@ -431,15 +469,21 @@ def parse_html_element
 
  if closing.nil?
  raise(
- ParseError,
- "Missing closing tag for <#{opening.name.value}> at #{opening.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Missing closing tag for <#{opening.name.value}> at #{opening.location}",
+ opening.location.start_line,
+ 0
+ )
  )
  end
 
  if closing.name.value != opening.name.value
  raise(
- ParseError,
- "Expected closing tag for <#{opening.name.value}> but got <#{closing.name.value}> at #{closing.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Expected closing tag for <#{opening.name.value}> but got <#{closing.name.value}> at #{closing.location}",
+ closing.location.start_line,
+ 0
+ )
  )
  end
 
@@ -462,8 +506,11 @@ def parse_erb_case(erb_node)
  unless erb_tag.is_a?(ErbCaseWhen) || erb_tag.is_a?(ErbElse) ||
  erb_tag.is_a?(ErbEnd)
  raise(
- ParseError,
- "Found no matching erb-tag to the if-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching erb-tag to the if-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
 
@@ -484,8 +531,11 @@ def parse_erb_case(erb_node)
  )
  else
  raise(
- ParseError,
- "Found no matching when- or else-tag to the case-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching when- or else-tag to the case-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
  end
@@ -501,8 +551,11 @@ def parse_erb_if(erb_node)
 
  unless erb_tag.is_a?(ErbControl) || erb_tag.is_a?(ErbEnd)
  raise(
- ParseError,
- "Found no matching erb-tag to the if-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching erb-tag to the if-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
 
@@ -530,8 +583,11 @@ def parse_erb_if(erb_node)
  )
  else
  raise(
- ParseError,
- "Found no matching elsif- or else-tag to the if-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching elsif- or else-tag to the if-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
  end
@@ -543,8 +599,11 @@ def parse_erb_else(erb_node)
 
  unless erb_end.is_a?(ErbEnd)
  raise(
- ParseError,
- "Found no matching end-tag for the else-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching end-tag for the else-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
 
@@ -582,8 +641,11 @@ def parse_erb_tag
 
  if !closing_tag.is_a?(ErbClose)
  raise(
- ParseError,
- "Found no matching closing tag for the erb-tag at #{opening_tag.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching closing tag for the erb-tag at #{opening_tag.location}",
+ opening_tag.location.start_line,
+ 0
+ )
  )
  end
 
@@ -615,8 +677,11 @@ def parse_erb_tag
 
  unless erb_end.is_a?(ErbEnd)
  raise(
- ParseError,
- "Found no matching end-tag for the do-tag at #{erb_node.location}"
+ SyntaxTree::Parser::ParseError.new(
+ "Found no matching end-tag for the do-tag at #{erb_node.location}",
+ erb_node.location.start_line,
+ 0
+ )
  )
  end
 
@@ -630,13 +695,23 @@ def parse_erb_tag
  erb_node
  end
  end
- rescue MissingTokenError => error
+ rescue SyntaxTree::Parser::ParseError => error
  # If we have parsed tokens that we cannot process after we parsed <%, we should throw a ParseError
  # and not let it be handled by a `maybe`.
  if opening_tag
+ message =
+ if error.message.include?("Could not parse ERB-tag")
+ error.message
+ else
+ "Could not parse ERB-tag: #{error.message}"
+ end
+
  raise(
- ParseError,
- "Could not parse ERB-tag at #{opening_tag.location}"
+ SyntaxTree::Parser::ParseError.new(
+ message,
+ opening_tag.location.start_line,
+ 0
+ )
  )
  else
  raise(error)

test/erb_test.rb

@@ -12,19 +12,19 @@ def test_empty_file
  end
 
  def test_missing_erb_end_tag
- assert_raises(SyntaxTree::ERB::Parser::ParseError) do
+ assert_raises(SyntaxTree::Parser::ParseError) do
  ERB.parse("<% if no_end_tag %>")
  end
  end
 
  def test_missing_erb_block_end_tag
- assert_raises(SyntaxTree::ERB::Parser::ParseError) do
+ assert_raises(SyntaxTree::Parser::ParseError) do
  ERB.parse("<% no_end_tag do %>")
  end
  end
 
  def test_missing_erb_case_end_tag
- assert_raises(SyntaxTree::ERB::Parser::ParseError) do
+ assert_raises(SyntaxTree::Parser::ParseError) do
  ERB.parse("<% case variabel %>\n<% when 1>\n Hello\n")
  end
  end
@@ -35,6 +35,23 @@ def test_erb_code_with_non_ascii
  assert_instance_of(SyntaxTree::ERB::ErbNode, parsed.elements.first)
  end
 
+ def test_erb_errors
+ example = <<-HTML
+<ul>
+<% if @items.each do |i|%>
+<li><%= i %></li>
+<% end.blank? %>
+<li>No items</li>
+<% end %>
+</ul>
+HTML
+ ERB.parse(example)
+ rescue SyntaxTree::Parser::ParseError => error
+ assert_equal(2, error.lineno)
+ assert_equal(0, error.column)
+ assert_match(/Could not parse ERB-tag/, error.message)
+ end
+
  def test_if_and_end_in_same_output_tag_short
  source = "<%= if true\n what\nend %>"
  expected = "<%= what if true %>\n"