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/*
* MRustC - Rust Compiler
* - By John Hodge (Mutabah/thePowersGang)
*
* expand/env.cpp
* - env! and option_env! macros
*/
#include <synext_macro.hpp>
#include <parse/common.hpp>
#include <parse/ttstream.hpp>
#include <ast/expr.hpp> // ExprNode_*
#include <synext.hpp> // for Expand_BareExpr
namespace {
// Read a string out of the input stream
::std::string get_string(const Span& sp, const AST::Crate& crate, AST::Module& mod, const TokenTree& tt) {
auto lex = TTStream(tt);
auto n = Parse_ExprVal(lex);
ASSERT_BUG(sp, n, "No expression returned");
if( lex.lookahead(0) != TOK_EOF ) {
ERROR(sp, E0000, "Unexpected token after string literal - " << lex.getToken());
}
Expand_BareExpr(crate, mod, n);
auto* string_np = dynamic_cast<AST::ExprNode_String*>(&*n);
if( !string_np ) {
ERROR(sp, E0000, "Expected a string literal - got " << *n);
}
return mv$( string_np->m_value );
}
}
class CExpanderEnv:
public ExpandProcMacro
{
::std::unique_ptr<TokenStream> expand(const Span& sp, const AST::Crate& crate, const ::std::string& ident, const TokenTree& tt, AST::Module& mod) override
{
if( ident != "" )
ERROR(sp, E0000, "env! doesn't take an ident");
::std::string varname = get_string(sp, crate, mod, tt);
const char* var_val_cstr = getenv(varname.c_str());
if( !var_val_cstr ) {
ERROR(sp, E0000, "Environment variable '" << varname << "' not defined");
}
return box$( TTStreamO(TokenTree(Token(TOK_STRING, var_val_cstr))) );
}
};
class CExpanderOptionEnv:
public ExpandProcMacro
{
::std::unique_ptr<TokenStream> expand(const Span& sp, const AST::Crate& crate, const ::std::string& ident, const TokenTree& tt, AST::Module& mod) override
{
if( ident != "" )
ERROR(sp, E0000, "option_env! doesn't take an ident");
::std::string varname = get_string(sp, crate, mod, tt);
const char* var_val_cstr = getenv(varname.c_str());
if( !var_val_cstr ) {
::std::vector< TokenTree> rv;
rv.reserve(7);
rv.push_back( Token(TOK_IDENT, "None") );
rv.push_back( Token(TOK_DOUBLE_COLON) );
rv.push_back( Token(TOK_LT) );
rv.push_back( Token(TOK_AMP) );
rv.push_back( Token(TOK_LIFETIME, "static") );
rv.push_back( Token(TOK_IDENT, "str") );
rv.push_back( Token(TOK_GT) );
return box$( TTStreamO(TokenTree( {}, mv$(rv) )) );
}
else {
::std::vector< TokenTree> rv;
rv.reserve(4);
rv.push_back( Token(TOK_IDENT, "Some") );
rv.push_back( Token(TOK_PAREN_OPEN) );
rv.push_back( Token(TOK_STRING, var_val_cstr) );
rv.push_back( Token(TOK_PAREN_CLOSE) );
return box$( TTStreamO(TokenTree( {}, mv$(rv) )) );
}
}
};
STATIC_MACRO("env", CExpanderEnv);
STATIC_MACRO("option_env", CExpanderOptionEnv);
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