Initial revision

1 files changed, 29 insertions, 0 deletions

diff --git a/zwgc/substitute.h b/zwgc/substitute.h
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+++ b/zwgc/substitute.h
@@ -0,0 +1,29 @@
+#ifndef substitute_MODULE
+#define substitute_MODULE
+
+#include "new_string.h"
+
+/*
+ *    string substitute(string (*lookup)(string); string text)
+ *        Effects: returns the result of expanding all variable
+ *                 references in text using lookup.  Example:
+ *                 "test $foo.$bar baz" would be translated to
+ *                 "text <foo>.<bar> baz" where "<foo>" is the value of
+ *                 lookup("foo") and "<bar>" is the value of lookup("bar").
+ *                 Variables are case sensitive and have the form
+ *                 {identifier_char}+ where identifier_char is defined
+ *                 in lexer.h by is_identifier_char.  $(foo) and
+ *                 ${foo} are alternate forms for $foo.  In particular,
+ *                 ${foo}bar is a reference to foo followed by "bar" while
+ *                 $foobar is a reference to foobar.  Incomplete variable
+ *                 references like $(foo bar are displayed as if they
+ *                 were not variable references.  To allow quoting, "$$"
+ *                 is translated to "$".  Only the first
+ *                 MAX_IDENTIFIER_LENGTH characters of an identifier are
+ *                 significant.  The strings returned by lookup are not
+ *                 modified in any way or freed.
+ */
+
+extern string substitute();
+
+#endif