From b808c255b6a9ddba085bf5646e7d20ec344f2e2d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 28 Apr 2020 08:48:53 +0200
Subject: Initial support for ad hoc recipes (still work in progress)

---
 libbuild2/script/lexer.hxx | 139 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 libbuild2/script/lexer.hxx

(limited to 'libbuild2/script/lexer.hxx')

diff --git a/libbuild2/script/lexer.hxx b/libbuild2/script/lexer.hxx
new file mode 100644
index 0000000..dbfdfcc
--- /dev/null
+++ b/libbuild2/script/lexer.hxx
@@ -0,0 +1,139 @@
+// file      : libbuild2/script/lexer.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_SCRIPT_LEXER_HXX
+#define LIBBUILD2_SCRIPT_LEXER_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/lexer.hxx>
+
+#include <libbuild2/script/token.hxx>
+
+namespace build2
+{
+  namespace script
+  {
+    struct lexer_mode: build2::lexer_mode
+    {
+      using base_type = build2::lexer_mode;
+
+      enum
+      {
+        command_expansion = base_type::value_next,
+        here_line_single,
+        here_line_double,
+
+        value_next
+      };
+
+      lexer_mode () = default;
+      lexer_mode (value_type v): base_type (v) {}
+      lexer_mode (base_type v): base_type (v) {}
+    };
+
+    // Actual redirects (as tokens) for the the <, <<, <<<, and >, >>, >>>
+    // aliases.
+    //
+    struct redirect_aliases
+    {
+      optional<token_type> l;   // <
+      optional<token_type> ll;  // <<
+      optional<token_type> lll; // <<<
+      optional<token_type> g;   // >
+      optional<token_type> gg;  // >>
+      optional<token_type> ggg; // >>>
+
+      // If the token type is a redirect alias then return the token type it
+      // resolves to and the passed token type otherwise. Note that it's the
+      // caller's responsibility to make sure that the corresponding alias is
+      // present (normally by not recognizing absent aliases as tokens).
+      //
+      token_type
+      resolve (token_type t) const noexcept
+      {
+        switch (t)
+        {
+        case token_type::in_l:    assert (l);   return *l;
+        case token_type::in_ll:   assert (ll);  return *ll;
+        case token_type::in_lll:  assert (lll); return *lll;
+        case token_type::out_g:   assert (g);   return *g;
+        case token_type::out_gg:  assert (gg);  return *gg;
+        case token_type::out_ggg: assert (ggg); return *ggg;
+        }
+
+        return t;
+      }
+    };
+
+    class lexer: public build2::lexer
+    {
+    public:
+      using base_lexer = build2::lexer;
+      using base_mode = build2::lexer_mode;
+
+      using redirect_aliases_type = script::redirect_aliases;
+
+      // Note that none of the name, redirect aliases, and escape arguments
+      // are copied.
+      //
+      lexer (istream& is,
+             const path_name& name,
+             lexer_mode m,
+             const redirect_aliases_type& ra,
+             const char* escapes = nullptr)
+          : base_lexer (is, name, 1 /* line */,
+                        nullptr     /* escapes */,
+                        false       /* set_mode */),
+            redirect_aliases (ra)
+      {
+        mode (m, '\0', escapes);
+      }
+
+      virtual void
+      mode (base_mode,
+            char = '\0',
+            optional<const char*> = nullopt,
+            uintptr_t = 0) override;
+
+      // Number of quoted (double or single) tokens since last reset.
+      //
+      size_t
+      quoted () const {return quoted_;}
+
+      void
+      reset_quoted (size_t q) {quoted_ = q;}
+
+      virtual token
+      next () override;
+
+    public:
+      const redirect_aliases_type& redirect_aliases;
+
+    protected:
+      lexer (istream& is, const path_name& name, uint64_t line,
+             const char* escapes,
+             bool set_mode,
+             const redirect_aliases_type& ra)
+          : base_lexer (is, name, line, escapes, set_mode),
+            redirect_aliases (ra) {}
+
+      // Return the next token if it is a command operator (|, ||, &&,
+      // redirect, or cleanup) and nullopt otherwise.
+      //
+      optional<token>
+      next_cmd_op (const xchar&, // The token first character (last got char).
+                   bool sep);    // The token is separated.
+
+    private:
+      token
+      next_line ();
+
+    protected:
+      size_t quoted_;
+    };
+  }
+}
+
+#endif // LIBBUILD2_SCRIPT_LEXER_HXX
-- 
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