Erythro/src/Statements.c

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/*************/
/*GEMWIRE */
/* ERYTHRO*/
/*************/
#include <Defs.h>
#include <Data.h>
/*
* Handles the declaration of a type of a variable.
* int newVar;
*
* It verifies that we have the `int` keyword followed by a
* unique, non-keyword identifier.
*
* It then stores this variable into the symbol table.
*
* //TODO: Assemble this into the symbol table.
* //TODO: int i = 5;
*
*/
void BeginVariableDeclaration(int Type) {
int ID;
//printf("type: %s\n", Types[Type]);
while(1) {
//printf("Identifier: %s\n", CurrentIdentifier);
printf("Adding symbol %s of type %s.\n", CurrentIdentifier, TypeNames[Type]);
ID = AddSymbol(CurrentIdentifier, Type, ST_VAR);
AsNewSymb(ID);
if(CurrentToken.type == LI_SEMIC) {
printf("\tEnd of variables to declare in this statement\n");
Tokenise(&CurrentToken);
return;
}
if(CurrentToken.type == LI_COM) {
printf("\t\tStatement appears to continue. Integrating new variable.\n");
Tokenise(&CurrentToken);
VerifyToken(TY_IDENTIFIER, "ident");
continue;
}
DieDecimal("\nExpected ; after identifier, found", CurrentToken.type);
}
}
struct ASTNode* ParseFunction(int Type) {
struct ASTNode* Tree;
struct ASTNode* FinalStatement;
int SymbolSlot, BreakLabel;
printf("\nIdentified function %s\n", CurrentIdentifier);
BreakLabel = NewLabel();
SymbolSlot = AddFunctionSymbol(CurrentIdentifier, Type, ST_FUNC, BreakLabel);
CurrentFunction = SymbolSlot;
VerifyToken(LI_LPARE, "(");
VerifyToken(LI_RPARE, ")");
Tree = ParseCompound();
if(Type != RET_VOID) {
// Functions with one statement have no composite node, so we have to check
FinalStatement = (Tree->Operation == OP_COMP) ? Tree->Right : Tree;
if(FinalStatement == NULL || FinalStatement->Operation != OP_RET) {
Die("Function with non-void type does not return");
}
}
return ConstructASTBranch(OP_FUNC, Tree->ExprType, Tree, SymbolSlot);
}
/*
* Handles the logic for return.
* //TODO: No brackets
* //TODO: Type inference
*
*
*/
struct ASTNode* ReturnStatement() {
struct ASTNode* Tree;
int ReturnType, FunctionType;
if(Symbols[CurrentFunction].Type == RET_VOID)
Die("Attempt to return from void function");
VerifyToken(KW_RETURN, "return");
VerifyToken(LI_LPARE, "("); // TODO: Make optional! Reject?
Tree = ParsePrecedenceASTNode(0);
ReturnType = Tree->ExprType;
FunctionType = Symbols[CurrentFunction].Type;
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Tree = MutateType(Tree, FunctionType, 0);
if(!Tree)
Die("Returning a value of incorrect type for function");
if(ReturnType)
Tree = ConstructASTBranch(ReturnType, FunctionType, Tree, 0);
Tree = ConstructASTBranch(OP_RET, RET_NONE, Tree, 0);
printf("\t\tReturning from function %s\n", Symbols[CurrentFunction].Name);
VerifyToken(LI_RPARE, ")"); // TODO: OPTIONALISE!
return Tree;
}
/*
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* Handles Identifiers.
*
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* This is called for any of:
* - Calling a function
* - Assigning an lvalue variable
* - Performing arithmetic on a variable
* - Performing arithmetic with the return values of function calls
*
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* For the case where you're assigning an l-value;
* You can assign with another assignment,
* a statement, a function or a literal.
*
*/
struct ASTNode* ParseIdentifier() {
struct ASTNode* Left, *Right, *Tree;
int LeftType, RightType;
int ID;
VerifyToken(TY_IDENTIFIER, "ident");
printf("\t\tAfter parsing, the identifier name is %s, id %d in the symbol table.\n", CurrentIdentifier, FindSymbol(CurrentIdentifier));
if(CurrentToken.type == LI_LPARE)
return CallFunction();
if((ID = FindSymbol(CurrentIdentifier)) == -1) {
printf("Symbol %s not in table. Table contents: %s, %s\n", CurrentIdentifier, Symbols[0].Name, Symbols[1].Name);
DieMessage("Undeclared Variable ", CurrentIdentifier);
}
Right = ConstructASTLeaf(LV_IDENT, Symbols[ID].Type, ID);
VerifyToken(LI_EQUAL, "=");
Left = ParsePrecedenceASTNode(0);
LeftType = Left->ExprType;
RightType = Right->ExprType;
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Left = MutateType(Left, RightType, 0);
if(!Left)
Die("Incompatible types in assignment");
if(LeftType)
Left = ConstructASTBranch(LeftType, Right->ExprType, Left, 0);
Tree = ConstructASTNode(OP_ASSIGN, RET_INT, Left, NULL, Right, 0);
return Tree;
}
struct ASTNode* IfStatement() {
struct ASTNode* Condition, *True, *False = NULL;
VerifyToken(KW_IF, "if");
VerifyToken(LI_LPARE, "(");
Condition = ParsePrecedenceASTNode(0);
// Limit if(x) to =? != < > <= =>
// No null checking, no arithmetic, no functions.
// TODO: this
if(Condition->Operation < OP_EQUAL || Condition->Operation > OP_GREATE)
Die("Invalid Comparison in if statement");
VerifyToken(LI_RPARE, ")");
True = ParseCompound();
if(CurrentToken.type == KW_ELSE) {
Tokenise(&CurrentToken);
False = ParseCompound();
}
return ConstructASTNode(OP_IF, RET_NONE, Condition, True, False, 0);
}
struct ASTNode* WhileStatement() {
struct ASTNode* Condition, *Body;
VerifyToken(KW_WHILE, "while");
VerifyToken(LI_LPARE, "(");
Condition = ParsePrecedenceASTNode(0);
if(Condition->Operation < OP_EQUAL || Condition->Operation > OP_GREATE)
Die("Bad Comparison inside while()");
VerifyToken(LI_RPARE, ")");
Body = ParseCompound();
return ConstructASTNode(OP_LOOP, RET_NONE, Condition, NULL, Body, 0);
}
struct ASTNode* ForStatement() {
// for (preop; condition; postop) {
// body
//}
struct ASTNode* Condition, *Body;
struct ASTNode* Preop, *Postop;
struct ASTNode* Tree;
VerifyToken(KW_FOR, "for");
VerifyToken(LI_LPARE, "(");
Preop = ParseStatement();
VerifyToken(LI_SEMIC, ";");
Condition = ParsePrecedenceASTNode(0);
if(Condition->Operation < OP_EQUAL || Condition->Operation > OP_GREATE)
Die("Bad comparison in for");
VerifyToken(LI_SEMIC, ";");
Postop = ParseStatement();
VerifyToken(LI_RPARE, ")");
Body = ParseCompound();
// We need to be able to skip over the body and the postop, so we group them together.
Tree = ConstructASTNode(OP_COMP, RET_NONE, Body, NULL, Postop, 0);
// We need to be able to jump to the top of the condition and fall through to the body,
// so we group it with the last block
Tree = ConstructASTNode(OP_LOOP, RET_NONE, Condition, NULL, Tree, 0);
// We need to append the postop to the loop, to form the final for loop
return ConstructASTNode(OP_COMP, RET_NONE, Preop, NULL, Tree, 0);
}
struct ASTNode* PrintStatement(void) {
struct ASTNode* Tree;
int LeftType, RightType;
VerifyToken(KW_PRINT, "print");
Tree = ParsePrecedenceASTNode(0);
LeftType = RET_INT;
RightType = Tree->ExprType;
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Tree = MutateType(Tree, RightType, 0);
if(!Tree)
DieDecimal("Attempting to print an invalid type:", RightType);
if(RightType)
Tree = ConstructASTBranch(RightType, RET_INT, Tree, 0);
Tree = ConstructASTBranch(OP_PRINT, RET_NONE, Tree, 0);
//ParseAST(Tree);
return Tree;
}
struct ASTNode* PrefixStatement() {
struct ASTNode* Tree;
switch (CurrentToken.type) {
case LI_AMP:
Tokenise(&CurrentToken);
// To allow things like:
// x = &&y;
// We need to recursively parse prefixes;
Tree = PrefixStatement();
if(Tree->Operation != REF_IDENT)
Die("& must be followed by another & or an identifier.");
Tree->Operation = OP_ADDRESS;
Tree->ExprType = PointerTo(Tree->ExprType);
break;
case AR_STAR:
Tokenise(&CurrentToken);
Tree = PrefixStatement();
if(Tree->Operation != REF_IDENT && Tree->Operation != OP_DEREF)
Die("* must be followed by another * or an identifier.");
Tree = ConstructASTBranch(OP_DEREF, ValueAt(Tree->ExprType), Tree, 0);
break;
default:
Tree = ParsePrimary();
}
return Tree;
}