From 6d4f9a216c68ed9d1c93855a3864206936cfd937 Mon Sep 17 00:00:00 2001
From: Marcel Greter <marcel.greter@ocbnet.ch>
Date: Sat, 9 Jan 2016 19:31:26 +0100
Subject: [PATCH] improve parsing of special functions

---
 src/constants.cpp |  1 +
 src/constants.hpp |  1 +
 src/eval.cpp      |  7 +++----
 src/prelexer.cpp  | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 src/prelexer.hpp  |  4 ++++
 5 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/src/constants.cpp b/src/constants.cpp
index cffc519773..f52eda44f7 100644
--- a/src/constants.cpp
+++ b/src/constants.cpp
@@ -87,6 +87,7 @@ namespace Sass {
     extern const char odd_kwd[]          = "odd";
     extern const char progid_kwd[]       = "progid";
     extern const char expression_kwd[]   = "expression";
+    extern const char calc_fn_kwd[]      = "calc";
     extern const char calc_kwd[]         = "calc(";
     extern const char moz_calc_kwd[]     = "-moz-calc(";
     extern const char webkit_calc_kwd[]  = "-webkit-calc(";
diff --git a/src/constants.hpp b/src/constants.hpp
index 21d416025d..99a410de86 100644
--- a/src/constants.hpp
+++ b/src/constants.hpp
@@ -89,6 +89,7 @@ namespace Sass {
     extern const char progid_kwd[];
     extern const char expression_kwd[];
     extern const char calc_kwd[];
+    extern const char calc_fn_kwd[];
     extern const char moz_calc_kwd[];
     extern const char webkit_calc_kwd[];
     extern const char ms_calc_kwd[];
diff --git a/src/eval.cpp b/src/eval.cpp
index 0d8a2c42fe..fa42c42650 100644
--- a/src/eval.cpp
+++ b/src/eval.cpp
@@ -882,10 +882,9 @@ namespace Sass {
       bind(std::string("Function"), c->name(), params, args, &ctx, &fn_env, this);
       Backtrace here(backtrace(), c->pstate(), ", in function `" + c->name() + "`");
       exp.backtrace_stack.push_back(&here);
-      // if it's user-defined, eval the body
-      if (body) { result = body->perform(this); }
-      // if it's native, invoke the underlying CPP function
-      else { result = func(fn_env, *env, ctx, def->signature(), c->pstate(), backtrace()); }
+      // eval the body if user-defined or special, invoke underlying CPP function if native
+      if (body && !Prelexer::re_special_fun(c->name().c_str())) { result = body->perform(this); }
+      else if (func) { result = func(fn_env, *env, ctx, def->signature(), c->pstate(), backtrace()); }
       if (!result) error(std::string("Function ") + c->name() + " did not return a value", c->pstate());
       exp.backtrace_stack.pop_back();
     }
diff --git a/src/prelexer.cpp b/src/prelexer.cpp
index f50519ddd8..79c16519be 100644
--- a/src/prelexer.cpp
+++ b/src/prelexer.cpp
@@ -296,7 +296,7 @@ namespace Sass {
       bool was_number = false;
       const char* pos = src;
       while (src) {
-        if (pos = alternatives < quoted_string, identifier, percentage, hex >(src)) {
+        if ((pos = alternatives < quoted_string, identifier, percentage, hex >(src))) {
           was_number = false;
           src = pos;
         } else if (!was_number && !exactly<'+'>(src) && (pos = alternatives < dimension, number >(src))) {
@@ -1129,6 +1129,41 @@ namespace Sass {
       return sequence< number, optional_spaces, exactly<'/'>, optional_spaces, number >(src);
     }
 
+    // lexer special_fn: these functions cannot be overloaded
+    // (/((-[\w-]+-)?(calc|element)|expression|progid:[a-z\.]*)\(/i)
+    const char* re_special_fun(const char* src) {
+      return sequence <
+        optional <
+          sequence <
+            exactly <'-'>,
+            one_plus <
+              alternatives <
+                alpha,
+                exactly <'+'>,
+                exactly <'-'>
+              >
+            >
+          >
+        >,
+        alternatives <
+          exactly < calc_fn_kwd >,
+          exactly < expression_kwd >,
+          sequence <
+            sequence <
+              exactly < progid_kwd >,
+              exactly <':'>
+            >,
+            zero_plus <
+              alternatives <
+                char_range <'a', 'z'>,
+                exactly <'.'>
+              >
+            >
+          >
+        >
+      >(src);
+    }
+
     template <size_t size, prelexer mx, prelexer pad>
     const char* padded_token(const char* src)
     {
@@ -1159,5 +1194,13 @@ namespace Sass {
       return pos;
     }
 
+    template <char min, char max>
+    const char* char_range(const char* src)
+    {
+      if (*src < min) return 0;
+      if (*src > max) return 0;
+      return src + 1;
+    }
+
   }
 }
diff --git a/src/prelexer.hpp b/src/prelexer.hpp
index e7156f3723..d22ccac170 100644
--- a/src/prelexer.hpp
+++ b/src/prelexer.hpp
@@ -253,6 +253,7 @@ namespace Sass {
     const char* re_nothing(const char* src);
     const char* re_type_selector2(const char* src);
 
+    const char* re_special_fun(const char* src);
 
     const char* kwd_warn(const char* src);
     const char* kwd_err(const char* src);
@@ -423,6 +424,9 @@ namespace Sass {
     template <size_t min, size_t max, prelexer mx>
     const char* minmax_range(const char* src);
 
+    template <char min, char max>
+    const char* char_range(const char* src);
+
   }
 }