This section covers functions for querying and comparing values on the Tea stack. These functions allow C code to inspect the type of a value, obtain readable type names and test for specific categories of values.

tea_get_mask()

int tea_get_mask(tea_State* T, int index);

Returns a bitmask corresponding to the type of the value at index. The mask is a single bit set in the position associated with the value’s type (e.g. TEA_MASK_NUMBER, TEA_MASK_STRING). If the slot has no value (i.e. it is empty), TEA_MASK_NONE is returned.

This is useful for accepting multiple types in a single check, by OR-ing each type mask together.

Arguments

  • T: Teascript state
  • index: Stack index of the value to inspect

Returns

A single-bit type mask, or TEA_MASK_NONE if the slot is non-existent.

Example

tea_push_number(T, 3.14);
tea_push_string(T, "tea");   /* [3.14, "tea"] */

if(tea_get_mask(T, -1) & (TEA_MASK_STRING | TEA_MASK_NUMBER))
{
    /* Either a string or a number: accepted */
}

See Also

tea_get_type, tea_is_mask, tea_typeof

tea_get_type()

int tea_get_type(tea_State* T, int index);

Returns the type of the value at index as one of the TEA_TYPE_* constants. If the slot is empty, TEA_TYPE_NONE is returned.

Arguments

  • T: Teascript state
  • index: Stack index of the value to inspect

Returns

The TEA_TYPE_* constant describing the value’s type, or TEA_TYPE_NONE if the slot has no value.

Example

tea_push_integer(T, 42);

if(tea_get_type(T, -1) == TEA_TYPE_NUMBER)
{
    tea_Number n = tea_get_number(T, -1);
}

See Also

tea_get_mask, tea_typeof, tea_check_type

tea_is_object()

bool tea_is_object(tea_State* T, int index);

Gives true if the value at index is a garbage-collected object (string, list, map, function, module, class, instance, userdata, etc.), and false otherwise. Primitive values such as numbers, booleans, pointers and nil are not considered objects.

Arguments

  • T: Teascript state
  • index: Stack index of the value to test

Returns

true if the value is a GC object, false otherwise.

Example

tea_push_string(T, "hello");
tea_push_integer(T, 123);

bool a = tea_is_object(T, -2);  /* true  */
bool b = tea_is_object(T, -1);  /* false */

See Also

tea_is_cfunction, tea_get_type

tea_is_cfunction()

bool tea_is_cfunction(tea_State* T, int index);

Gives true if the value at index is a C function (a function created via tea_push_cfunction, tea_push_cclosure, or one of the registration helpers), and false otherwise. Teascript functions written in Tea are not considered C functions.

Arguments

  • T: Teascript state
  • index: Stack index of the value to test

Returns

true if the value is a C function, false otherwise.

Example

tea_push_cfunction(T, my_callback, 0, 0);

if(tea_is_cfunction(T, -1))
{
    tea_CFunction fn = tea_to_cfunction(T, -1);
    /* ... */
}

See Also

tea_is_object, tea_to_cfunction, tea_check_cfunction

tea_typeof()

const char* tea_typeof(tea_State* T, int index);

Provides a human-readable, NUL terminated C string describing the type of the value at index (e.g. "number", "string", "list"). If the slot has no value, the string "no value" is given. The provided string is owned by the interpreter and must not be modified.

This is primarily intended for diagnostics, error messages, and debugging output.

Arguments

  • T: Teascript state
  • index: Stack index of the value to inspect

Returns

A constant string naming the value’s type, or "no value" if the slot is non-existent.

Example

tea_push_map(T);

tea_push_fstring(T, "unexpected type: %s", tea_typeof(T, -2));
/* Pushes "unexpected type: map" */

See Also

tea_get_type, tea_get_mask

tea_equal()

bool tea_equal(tea_State* T, int index1, int index2);

Provides true if the values at index1 and index2 are equal, following Teascript equality semantics. This may invoke user-defined + operator method for instances and userdata, and therefore is not guaranteed to be side-effect free.

Both indices must refer to valid stack slots.

Arguments

  • T: Teascript state
  • index1: Stack index of the first (left) value
  • index2: Stack index of the second (right) value

Returns

true if the values are equal, false otherwise.

Example

tea_push_integer(T, 10);
tea_push_integer(T, 10);
tea_push_integer(T, 20);

bool ab = tea_equal(T, -3, -2);  /* true  */
bool ac = tea_equal(T, -3, -1);  /* false */

See Also

tea_rawequal

tea_rawequal()

bool tea_rawequal(tea_State* T, int index1, int index2);

Provides true if the values at index1 and index2 are equal without invoking any defined operator method. For object types, this performs a reference comparison (identity), not a structural one. This function never calls user code and has no side effects.

Both indices must refer to valid stack slots.

Arguments

  • T: Teascript state
  • index1: Stack index of the first (left) value
  • index2: Stack index of the second (right) value

Returns

true if the values are raw-equal, false otherwise.

Example

tea_push_string(T, "tea");
tea_push_string(T, "tea");   /* Interned strings: same object */
tea_push_string(T, "coffee");

bool a = tea_rawequal(T, -3, -2);  /* true  */
bool b = tea_rawequal(T, -3, -1);  /* false */

See Also

tea_equal, tea_get_type