Implement lexical analyzer for the CLI language

1 files changed, 413 insertions, 0 deletions

diff --git a/cli/lexer.cxx b/cli/lexer.cxx
new file mode 100644
index 0000000..203667a
--- /dev/null
+++ b/cli/lexer.cxx
@@ -0,0 +1,413 @@
+// file      : cli/lexer.cxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <iostream>
+
+#include "lexer.hxx"
+
+using namespace std;
+
+Lexer::
+Lexer (istream& is, string const& id)
+    : loc_ ("C"),
+      is_ (is),
+      id_ (id),
+      l_ (1),
+      c_(1),
+      eos_ (false),
+      include_ (false)
+{
+  keyword_map_["include"]   = Token::k_include;
+  keyword_map_["namespace"] = Token::k_namespace;
+  keyword_map_["class"]     = Token::k_class;
+  keyword_map_["signed"]    = Token::k_signed;
+  keyword_map_["unsigned"]  = Token::k_unsigned;
+  keyword_map_["bool"]      = Token::k_bool;
+  keyword_map_["char"]      = Token::k_char;
+  keyword_map_["wchar_t"]   = Token::k_wchar;
+  keyword_map_["short"]     = Token::k_short;
+  keyword_map_["int"]       = Token::k_int;
+  keyword_map_["long"]      = Token::k_long;
+  keyword_map_["float"]     = Token::k_float;
+  keyword_map_["double"]    = Token::k_double;
+}
+
+Lexer::Char Lexer::
+get ()
+{
+  // When is_.get () returns eof, the failbit is also set (stupid,
+  // isn't?) which may trigger an exception. To work around this
+  // we will call peek() first and only call get() if it is not
+  // eof. But we can only call peek() on eof once; any subsequent
+  // calls will spoil the failbit (even more stupid).
+  //
+  Char c (peek ());
+
+  if (!is_eos (c))
+  {
+    is_.get ();
+
+    if (c == '\n')
+    {
+      l_++;
+      c_ = 1;
+    }
+    else
+      c_++;
+  }
+
+  return c;
+}
+
+Lexer::Char Lexer::
+peek ()
+{
+  if (eos_)
+    return Char (Char::Traits::eof (), l_, c_);
+  else
+  {
+    Char::IntType i (is_.peek ());
+
+    if (i == Char::Traits::eof ())
+      eos_ = true;
+
+    return Char (i, l_, c_);
+  }
+}
+
+Token Lexer::
+next ()
+{
+  while (true) // Recovery loop.
+  {
+    bool include (include_);
+    include_ = false;
+
+    skip_spaces ();
+
+    Char c (get ());
+
+    if (is_eos (c))
+      return Token (c.line (), c.column ());
+
+    try
+    {
+      switch (c)
+      {
+      case '\'':
+        {
+          return char_literal (c);
+        }
+      case '\"':
+        {
+          if (include)
+            return path_literal (c);
+          else
+            return string_literal (c);
+        }
+      case '<':
+        {
+          if (include)
+            return path_literal (c);
+
+          break;
+        }
+      case ';':
+        {
+          return Token (Token::p_semi, c.line (), c.column ());
+        }
+      case ',':
+        {
+          return Token (Token::p_comma, c.line (), c.column ());
+        }
+      case ':':
+        {
+          return Token (Token::p_colon, c.line (), c.column ());
+        }
+      case '{':
+        {
+          return Token (Token::p_lcbrace, c.line (), c.column ());
+        }
+      case '}':
+        {
+          return Token (Token::p_rcbrace, c.line (), c.column ());
+        }
+      case '(':
+        {
+          return Token (Token::p_lparen, c.line (), c.column ());
+        }
+      case ')':
+        {
+          return Token (Token::p_rparen, c.line (), c.column ());
+        }
+      case '=':
+        {
+          return Token (Token::p_eq, c.line (), c.column ());
+        }
+      case '|':
+        {
+          return Token (Token::p_or, c.line (), c.column ());
+        }
+      case '-':
+        {
+          // This can be a beginning of an identifier or a an integer
+          // literal. Figure out which one it is.
+          //
+          Char p (peek ());
+
+          if (is_dec_digit (p))
+            return int_literal (get (), true, c.line (), c.column ());
+          else if (is_space (p))
+          {
+            skip_spaces ();
+            p = peek ();
+
+            if (is_dec_digit (p))
+              return int_literal (get (), true, c.line (), c.column ());
+
+            // Stray '-'.
+            //
+            cerr << id_ << ':' << c.line () << ':' << c.column ()
+                 << ": error: unexpected character '-'" << endl;
+            throw invalid_input ();
+          }
+
+          break;
+        }
+      }
+
+      if (is_alpha (c) || c == '_' || c == '-' || c == '/')
+      {
+        return identifier (c);
+      }
+
+      if (is_dec_digit (c))
+      {
+        return int_literal (c);
+      }
+
+      cerr << id_ << ':' << c.line () << ':' << c.column ()
+           << ": error: unexpected character '" << c << "'" << endl;
+    }
+    catch (invalid_input const&)
+    {
+    }
+
+    // Try to recover.
+    //
+    do
+    {
+      c = get ();
+
+      if (is_eos (c))
+        return Token (c.line (), c.column ());
+    } while (c != ';');
+  }
+}
+
+void Lexer::
+skip_spaces ()
+{
+  for (Char c (peek ()); !is_eos (c) && is_space (c); c = peek ())
+    get ();
+}
+
+Token Lexer::
+identifier (Char c)
+{
+  size_t ln (c.line ()), cl (c.column ());
+  string lexeme;
+  lexeme += c;
+
+  bool check (c == '-' || c == '/');
+
+  for (c = peek ();
+       !is_eos (c) && (is_alnum (c) || c == '_' || c == '-');
+       c = peek ())
+  {
+    get ();
+    lexeme += c;
+  }
+
+  // Check for invalid identifiers.
+  //
+  if (check)
+  {
+    size_t i (1);
+
+    for (; i < lexeme.size (); ++i)
+      if (is_alnum (lexeme[i]) || lexeme[i] == '_')
+        break;
+
+    if (i == lexeme.size ())
+    {
+      cerr << id_ << ':' << c.line () << ':' << c.column () << ": error: "
+           << "invalid character sequence '" << lexeme << "'" << endl;
+      throw invalid_input ();
+    }
+  }
+
+  KeywordMap::const_iterator i (keyword_map_.find (lexeme));
+
+  if (i != keyword_map_.end ())
+  {
+    if (i->second == Token::k_include)
+      include_ = true;
+
+    return Token (i->second, ln, cl);
+  }
+
+  if (lexeme == "true" || lexeme == "false")
+    return Token (Token::t_bool_lit, lexeme, ln, cl);
+
+  return Token (Token::t_identifier, lexeme, ln, cl);
+}
+
+Token Lexer::
+int_literal (Char c, bool neg, size_t ml, size_t mc)
+{
+  size_t ln (neg ? ml : c.line ()), cl (neg ? mc : c.column ());
+  string lexeme;
+
+  if (neg)
+    lexeme += '-';
+
+  lexeme += c;
+
+  for (c = peek (); !is_eos (c) && is_dec_digit (c); c = peek ())
+  {
+    get ();
+    lexeme += c;
+  }
+
+  return Token (Token::t_int_lit, lexeme, ln, cl);
+}
+
+Token Lexer::
+char_literal (Char c)
+{
+  size_t ln (c.line ()), cl (c.column ());
+  string lexeme;
+  lexeme += c;
+
+  char p (c);
+
+  while (true)
+  {
+    c = get ();
+
+    if (is_eos (c))
+    {
+      cerr << id_ << ':' << c.line () << ':' << c.column () << ": error: "
+           << "end of stream reached while reading character literal" << endl;
+      throw invalid_input ();
+    }
+
+    lexeme += c;
+
+    if (c == '\'' && p != '\\')
+      break;
+
+    // We need to keep track of \\ escapings so we don't confuse
+    // them with \', as in '\\'.
+    //
+    if (c == '\\' && p == '\\')
+      p = '.';
+    else
+      p = c;
+  }
+
+  return Token (Token::t_char_lit, lexeme, ln, cl);
+}
+
+Token Lexer::
+string_literal (Char c)
+{
+  size_t ln (c.line ()), cl (c.column ());
+  string lexeme;
+  lexeme += c;
+
+  while (true)
+  {
+    lexeme += string_literal_trailer ();
+
+    // Check if there are more strings.
+    //
+    skip_spaces ();
+
+    c = peek ();
+
+    if (is_eos (c) || c != '"')
+      break;
+
+    get ();
+    lexeme += " \"";
+  }
+
+  return Token (Token::t_char_lit, lexeme, ln, cl);
+}
+
+string Lexer::
+string_literal_trailer ()
+{
+  string r;
+  char p ('"');
+
+  while (true)
+  {
+    Char c = get ();
+
+    if (is_eos (c))
+    {
+      cerr << id_ << ':' << c.line () << ':' << c.column () << ": error: "
+           << "end of stream reached while reading string literal" << endl;
+      throw invalid_input ();
+    }
+
+    r += c;
+
+    if (c == '"' && p != '\\')
+      break;
+
+    // We need to keep track of \\ escapings so we don't confuse
+    // them with \', as in '\\'.
+    //
+    if (c == '\\' && p == '\\')
+      p = '.';
+    else
+      p = c;
+  }
+
+  return r;
+}
+
+Token Lexer::
+path_literal (Char c)
+{
+  size_t ln (c.line ()), cl (c.column ());
+  string lexeme;
+  lexeme += c;
+
+  char end (c == '<' ? '>' : '"');
+
+  while (true)
+  {
+    c = get ();
+
+    if (is_eos (c))
+    {
+      cerr << id_ << ':' << c.line () << ':' << c.column () << ": error: "
+           << "end of stream reached while reading path literal" << endl;
+      throw invalid_input ();
+    }
+
+    lexeme += c;
+
+    if (c == end)
+      break;
+  }
+
+  return Token (Token::t_path_lit, lexeme, ln, cl);
+}