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#define XERR
#include "symtab.ih"
// d_var: each nesting level has its own entry.
// Level 0: global vars, level 1: parameters, level > 1: local vars
// at each level there is a vector<Var> containing the definitions of
// the variables: name, varType and location.
// location of:
// * global variables: their index in the global vector<Var>;
// * parameters: their index in the parameters vector<Var> + 0xc002
// * local variabless: 0xc000 - their index in d_locals, which is an array
// collecting all local variable types.
//
// see also README.stackframe
SemVal Symtab::defineVar(ExprType type, string const &name)
{
auto &variables = d_var.back(); // the variables at the current
// nestingLevel: the most recent VarVect
if ( // if name is defined at this
int idx = find(variables, name); // nestingLevel: error, existing
idx != -1 // name
)
{
Error::msg(Error::MULTIPLY_DEFINED) << name << "'\n";
return { type | e_var, 0 }; // return pseudo variable
}
int varIndex = variables.size(); // the newly defined variable's index
switch (d_var.size()) // select the variable's nesting level
{
case 1: // for global variables the varIndex
break; // is already OK
case 2: // for parameters: >= 0xc002
varIndex += 0xc000 + 2; // see README.stackframe
break;
default: // for local variables: < 0xc000
d_locals.push_back(type);
varIndex = 0xc000 - d_locals.size();
break;
}
// xerr("defining " << name << " at location " << hex <<
// as<uint16_t>(varIndex) << dec << ' ' << as<short>(varIndex));
variables.push_back({ name, type | e_var, as<uint16_t>(varIndex) });
return { type | e_var, varIndex }; // return the variable's index:
// non-negative values: global variables
// negative values: parameters or locals
}
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