wsstree.c

来自「The Kannel Open Source WAP and SMS gatew」· C语言 代码 · 共 1,501 行 · 第 1/4 页

/********************* Statements ***************************************/

/* Linearize the variable declaration list `list'. */
static void linearize_variable_init(WsCompiler *compiler, WsList *list,
                                    WsUInt32 line)
{
    WsNamespace *ns;
    WsListItem *li;

    /* For each variable, declared with this list. */
    for (li = list->head; li; li = li->next) {
        WsVarDec *vardec = li->data;

        ns = ws_variable_define(compiler, line, WS_TRUE, vardec->name);
        if (ns && vardec->expr) {
            ws_expr_linearize(compiler, vardec->expr);

            /* Emit an instruction to store the initialization
               value to the variable. */
            ws_asm_link(compiler,
                        ws_asm_variable(compiler, line, WS_ASM_P_STORE_VAR,
                                        ns->vindex));
        }
    }
}


void ws_stmt_linearize(WsCompiler *compiler, WsStatement *stmt)
{
    WsListItem *li;
    WsAsmIns *ins;

    switch (stmt->type) {
    case WS_STMT_BLOCK:
        for (li = stmt->u.block->head; li; li = li->next)
            ws_stmt_linearize(compiler, li->data);
        break;

    case WS_STMT_VARIABLE:
        linearize_variable_init(compiler, stmt->u.var, stmt->first_line);
        break;

    case WS_STMT_EMPTY:
        /* Nothing here. */
        break;

    case WS_STMT_EXPR:
        ws_expr_linearize(compiler, stmt->u.expr);

        /* Pop the expressions result from the stack.  Otherwise loops
           could eventually cause stack overflows. */
        ws_asm_link(compiler, ws_asm_ins(compiler, stmt->last_line, WS_ASM_POP));
        break;

    case WS_STMT_IF:
        {
            WsAsmIns *l_else = ws_asm_label(compiler,
                                            (stmt->u.s_if.s_else
                                             ? stmt->u.s_if.s_else->first_line
                                             : stmt->last_line));
            WsAsmIns *l_end = ws_asm_label(compiler, stmt->last_line);

            /* Linearize the expression. */
            ws_expr_linearize(compiler, stmt->u.s_if.expr);

            /* If the result is false, jump to the else-branch. */
            ws_asm_link(compiler, ws_asm_branch(compiler, stmt->first_line,
                                                WS_ASM_P_TJUMP, l_else));

            /* Else, execute the then-branch and jump to the end. */
            ws_stmt_linearize(compiler, stmt->u.s_if.s_then);
            ws_asm_link(compiler, ws_asm_branch(compiler, stmt->last_line,
                                                WS_ASM_P_JUMP, l_end));

            /* Then else-branch. */
            ws_asm_link(compiler, l_else);

            /* Linearize the else-branch if it is present. */
            if (stmt->u.s_if.s_else)
                ws_stmt_linearize(compiler, stmt->u.s_if.s_else);

            /* Insert the end label. */
            ws_asm_link(compiler, l_end);
        }
        break;

    case WS_STMT_FOR:
        {
            WsAsmIns *l_loop = ws_asm_label(compiler, stmt->first_line);
            WsAsmIns *l_cont = ws_asm_label(compiler, stmt->first_line);
            WsAsmIns *l_break = ws_asm_label(compiler, stmt->first_line);
            WsContBreak *cb;

            /* Store the labels to the compiler. */

            cb = ws_f_calloc(compiler->pool_stree, 1, sizeof(*cb));
            if (cb == NULL) {
                ws_error_memory(compiler);
                return;
            }

            cb->next = compiler->cont_break;
            compiler->cont_break = cb;

            cb->l_cont = l_cont;
            cb->l_break = l_break;

            /* Linearize the possible init code. */
            if (stmt->u.s_for.init)
                linearize_variable_init(compiler, stmt->u.s_for.init,
                                        stmt->first_line);
            else if (stmt->u.s_for.e1) {
                /* Linearize the init. */
                ws_expr_linearize(compiler, stmt->u.s_for.e1);

                /* Pop the result. */
                ws_asm_link(compiler, ws_asm_ins(compiler, stmt->first_line,
                                                 WS_ASM_POP));
            }

            /* Insert the loop label. */
            ws_asm_link(compiler, l_loop);

            /* Linearize the condition. */
            if (stmt->u.s_for.e2) {
                ws_expr_linearize(compiler, stmt->u.s_for.e2);

                /* If false, jump out. */
                ws_asm_link(compiler, ws_asm_branch(compiler, stmt->first_line,
                                                    WS_ASM_P_TJUMP, l_break));
            }

            /* Linearize the body statement. */
            ws_stmt_linearize(compiler, stmt->u.s_for.stmt);

            /* Link the continue label. */
            ws_asm_link(compiler, l_cont);

            /* Linearize the update expression. */
            if (stmt->u.s_for.e3) {
                ws_expr_linearize(compiler, stmt->u.s_for.e3);

                /* Pop the result. */
                ws_asm_link(compiler, ws_asm_ins(compiler, stmt->first_line,
                                                 WS_ASM_POP));
            }

            /* Jump to the loop label to check the condition. */
            ws_asm_link(compiler, ws_asm_branch(compiler, stmt->last_line,
                                                WS_ASM_P_JUMP, l_loop));

            /* Insert the break label. */
            ws_asm_link(compiler, l_break);

            /* Pop the cont-break block. */
            compiler->cont_break = compiler->cont_break->next;
        }
        break;

    case WS_STMT_WHILE:
        {
            WsAsmIns *l_cont = ws_asm_label(compiler, stmt->first_line);
            WsAsmIns *l_break = ws_asm_label(compiler,
                                             stmt->u.s_while.stmt->last_line);
            WsContBreak *cb;

            /* Store the labels to the compiler. */

            cb = ws_f_calloc(compiler->pool_stree, 1, sizeof(*cb));
            if (cb == NULL) {
                ws_error_memory(compiler);
                return;
            }

            cb->next = compiler->cont_break;
            compiler->cont_break = cb;

            cb->l_cont = l_cont;
            cb->l_break = l_break;

            /* Insert the continue label. */
            ws_asm_link(compiler, l_cont);

            /* Linearize the expression. */
            ws_expr_linearize(compiler, stmt->u.s_while.expr);

            /* If false, jump out. */
            ws_asm_link(compiler, ws_asm_branch(compiler, stmt->first_line,
                                                WS_ASM_P_TJUMP, l_break));

            /* Linearize the body statement. */
            ws_stmt_linearize(compiler, stmt->u.s_while.stmt);

            /* And jump to the continue label to check the expression. */
            ws_asm_link(compiler, ws_asm_branch(compiler, stmt->last_line,
                                                WS_ASM_P_JUMP, l_cont));

            /* Insert the break label. */
            ws_asm_link(compiler, l_break);

            /* Pop the cont-break block. */
            compiler->cont_break = compiler->cont_break->next;
        }
        break;

    case WS_STMT_CONTINUE:
        if (compiler->cont_break == NULL)
            ws_src_error(compiler, stmt->first_line,
                         "continue statement not within a loop");

        ws_asm_link(compiler, ws_asm_branch(compiler, stmt->first_line,
                                            WS_ASM_P_JUMP,
                                            compiler->cont_break->l_cont));
        break;

    case WS_STMT_BREAK:
        if (compiler->cont_break == NULL)
            ws_src_error(compiler, stmt->first_line,
                         "break statement not within a loop");

        ws_asm_link(compiler, ws_asm_branch(compiler, stmt->first_line,
                                            WS_ASM_P_JUMP,
                                            compiler->cont_break->l_break));
        break;

    case WS_STMT_RETURN:
        if (stmt->u.expr) {
            /* Linearize the return value and return it. */
            ws_expr_linearize(compiler, stmt->u.expr);
            ins = ws_asm_ins(compiler, stmt->first_line, WS_ASM_RETURN);
        } else
            /* Return an empty string. */
            ins = ws_asm_ins(compiler, stmt->first_line, WS_ASM_RETURN_ES);

        ws_asm_link(compiler, ins);
        break;
    }
}


/* Constructors. */

static WsStatement *stmt_alloc(WsCompiler *compiler, WsStatementType type,
                               WsUInt32 first_line, WsUInt32 last_line)
{
    WsStatement *stmt = ws_f_calloc(compiler->pool_stree, 1, sizeof(*stmt));

    if (stmt == NULL)
        ws_error_memory(compiler);
    else {
        stmt->type = type;
        stmt->first_line = first_line;
        stmt->last_line = last_line;
    }

    return stmt;
}


WsStatement *ws_stmt_block(WsCompiler *compiler, WsUInt32 fline,
                           WsUInt32 lline, WsList *block)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_BLOCK, fline, lline);

    if (stmt)
        stmt->u.block = block;

    return stmt;
}


WsStatement *ws_stmt_variable(WsCompilerPtr compiler, WsUInt32 line,
                              WsList *variables)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_VARIABLE, line, line);

    if (stmt)
        stmt->u.var = variables;

    return stmt;
}


WsStatement *ws_stmt_empty(WsCompiler *compiler, WsUInt32 line)
{
    return stmt_alloc(compiler, WS_STMT_EMPTY, line, line);
}


WsStatement *ws_stmt_expr(WsCompiler *compiler, WsUInt32 line,
                          WsExpression *expr)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_EXPR, line, line);

    if (stmt)
        stmt->u.expr = expr;

    return stmt;
}


WsStatement *ws_stmt_if(WsCompiler *compiler, WsUInt32 line,
                        WsExpression *expr, WsStatement *s_then,
                        WsStatement *s_else)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_IF, line, line);

    if (stmt) {
        stmt->u.s_if.expr = expr;
        stmt->u.s_if.s_then = s_then;
        stmt->u.s_if.s_else = s_else;
    }

    return stmt;
}


WsStatement *ws_stmt_for(WsCompilerPtr compiler, WsUInt32 line, WsList *init,
                         WsExpression *e1, WsExpression *e2, WsExpression *e3,
                         WsStatement *stmt_body)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_FOR, line, line);

    if (stmt) {
        stmt->u.s_for.init = init;
        stmt->u.s_for.e1 = e1;
        stmt->u.s_for.e2 = e2;
        stmt->u.s_for.e3 = e3;
        stmt->u.s_for.stmt = stmt_body;
    }

    return stmt;
}


WsStatement *ws_stmt_while(WsCompiler *compiler, WsUInt32 line,
                           WsExpression *expr, WsStatement *stmt_arg)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_WHILE, line, line);

    if (stmt) {
        stmt->u.s_while.expr = expr;
        stmt->u.s_while.stmt = stmt_arg;
    }

    return stmt;
}


WsStatement *ws_stmt_continue(WsCompiler *compiler, WsUInt32 line)
{
    return stmt_alloc(compiler, WS_STMT_CONTINUE, line, line);
}


WsStatement *ws_stmt_break(WsCompiler *compiler, WsUInt32 line)
{
    return stmt_alloc(compiler, WS_STMT_BREAK, line, line);
}


WsStatement *ws_stmt_return(WsCompilerPtr compiler, WsUInt32 line,
                            WsExpression *expr)
{
    WsStatement *stmt = stmt_alloc(compiler, WS_STMT_RETURN, line, line);

    if (stmt)
        stmt->u.expr = expr;

    return stmt;
}