1 files changed, 178 insertions, 0 deletions
diff --git a/src/mcpp-expression.c b/src/mcpp-expression.c
new file mode 100644
index 0000000..1f9532d
--- /dev/null
+++ b/src/mcpp-expression.c
@@ -0,0 +1,178 @@
+#include <defs.h>
+#include <mcpp-expr.h>
+
+/*
+ * The front end keeps the already established mcpu-cpp preprocessing order:
+ * handle the special defined operator first, expand macros second, then pass
+ * the resulting UCS-2 expression to the ZUBR parser generated from
+ * mcpp-expr.zubr.
+ */
+
+static int
+expr_identifier_start( __mpu_char16_t c )
+{
+  return( mcpu_pp_is_identifier_start(c) );
+}
+
+static int
+expr_identifier_char( __mpu_char16_t c )
+{
+  return( mcpu_pp_is_identifier_char(c) );
+}
+
+static int
+expr_space( __mpu_char16_t c )
+{
+  return( c == ' ' || c == '\t' || c == '\r' || c == '\n' ||
+          c == '\f' || c == '\v' );
+}
+
+static int
+append_defined_value( mcpu_macro_table *macros,
+                      const __mpu_char16_t *text, size_t length,
+                      size_t *pos, mcpu_text *output,
+                      const char *filename, unsigned line_number )
+{
+  size_t p = *pos;
+  size_t start;
+  size_t end;
+  int    parenthesized = 0;
+
+  while( p < length && expr_space(text[p]) ) ++p;
+  if( p < length && text[p] == '(' )
+  {
+    parenthesized = 1;
+    ++p;
+    while( p < length && expr_space(text[p]) ) ++p;
+  }
+
+  if( p >= length || !expr_identifier_start(text[p]) )
+  {
+    fprintf( stderr, "%s:%u: error: identifier expected after defined\n",
+             filename, line_number );
+    return( -1 );
+  }
+
+  start = p++;
+  while( p < length && expr_identifier_char(text[p]) ) ++p;
+  end = p;
+
+  while( p < length && expr_space(text[p]) ) ++p;
+  if( parenthesized )
+  {
+    if( p >= length || text[p] != ')' )
+    {
+      fprintf( stderr, "%s:%u: error: missing ')' after defined\n",
+               filename, line_number );
+      return( -1 );
+    }
+    ++p;
+  }
+
+  if( mcpu_text_append_ascii(
+        output, mcpu_macro_find(macros, text + start, end - start) ? "1" : "0") != 0 )
+    return( -1 );
+
+  *pos = p;
+  return( 0 );
+}
+
+static int
+replace_defined_operators( mcpu_macro_table *macros,
+                           const __mpu_char16_t *text, size_t length,
+                           mcpu_text *output,
+                           const char *filename, unsigned line_number )
+{
+  size_t         p = 0;
+  __mpu_char16_t quote = 0;
+  int            escaped = 0;
+
+  mcpu_text_free( output );
+  mcpu_text_init( output );
+
+  while( p < length )
+  {
+    __mpu_char16_t c = text[p];
+
+    if( quote )
+    {
+      if( mcpu_text_append_char(output, c) != 0 ) return( -1 );
+      if( escaped )
+        escaped = 0;
+      else if( c == '\\' )
+        escaped = 1;
+      else if( c == quote )
+        quote = 0;
+      ++p;
+      continue;
+    }
+
+    if( c == '\'' || c == '"' )
+    {
+      quote = c;
+      if( mcpu_text_append_char(output, c) != 0 ) return( -1 );
+      ++p;
+      continue;
+    }
+
+    if( expr_identifier_start(c) )
+    {
+      size_t start = p++;
+      while( p < length && expr_identifier_char(text[p]) ) ++p;
+
+      if( p - start == 7 &&
+          mcpu_text_equal_ascii(text + start, p - start, "defined") )
+      {
+        if( append_defined_value(macros, text, length, &p, output,
+                                 filename, line_number) != 0 )
+          return( -1 );
+      }
+      else if( mcpu_text_append(output, text + start, p - start) != 0 )
+        return( -1 );
+      continue;
+    }
+
+    if( mcpu_text_append_char(output, c) != 0 )
+      return( -1 );
+    ++p;
+  }
+
+  return( 0 );
+}
+
+int
+mcpp_eval_if_expression( mcpu_macro_table *macros,
+                         const __mpu_char16_t *text, size_t length,
+                         enum mcpu_language language,
+                         const mcpu_macro_expansion_context *context,
+                         const char *filename, unsigned line_number,
+                         int *result )
+{
+  mcpu_text defined;
+  mcpu_text expanded;
+  int       rc = -1;
+
+  if( macros == NULL || text == NULL || context == NULL ||
+      filename == NULL || result == NULL )
+  {
+    errno = EINVAL;
+    return( -1 );
+  }
+
+  mcpu_text_init( &defined );
+  mcpu_text_init( &expanded );
+
+  if( replace_defined_operators(macros, text, length, &defined,
+                                filename, line_number) != 0 ||
+      mcpu_macro_expand(macros, defined.data, defined.length,
+                        language, context, &expanded) != 0 )
+    goto done;
+
+  rc = mcpp_expr_parse( expanded.data, expanded.length,
+                        filename, line_number, context->options, result );
+
+done:
+  mcpu_text_free( &defined );
+  mcpu_text_free( &expanded );
+  return( rc );
+}