compile: Implicit 'once' for literal strings

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/compiling/compiling_methods.nit b/src/compiling/compiling_methods.nit
index 1253a51..2dfb4a4 100644 (file)
--- a/src/compiling/compiling_methods.nit
+++ b/src/compiling/compiling_methods.nit
@@ -1177,7 +1177,19 @@ redef class AStringFormExpr
        redef meth compile_expr(v)
        do
                compute_string_info
-               return meth_with_native.compile_constructor_call(v, stype , ["BOX_NativeString(\"{_cstring}\")", "TAG_Int({_cstring_length})"])
+               var i = v.new_number
+               var cvar = v.cfc.get_var
+               v.add_decl("static val_t once_value_{i} = NIT_NULL; /* Once value for string {cvar}*/")
+               v.add_instr("if (once_value_{i} != NIT_NULL) {cvar} = once_value_{i};")
+               v.add_instr("else \{")
+               v.indent
+               v.cfc.free_var(cvar)
+               var e = meth_with_native.compile_constructor_call(v, stype , ["BOX_NativeString(\"{_cstring}\")", "TAG_Int({_cstring_length})"])
+               v.add_assignment(cvar, e)
+               v.add_instr("once_value_{i} = {cvar};")
+               v.unindent
+               v.add_instr("}")
+               return cvar
        end
 
        # The raw string value