gr: Add is_{zero,one,neg_one} to contexts

Author: Tom-Hubrecht

src/flint/types/_gr.pxd

@@ -378,6 +378,18 @@ cdef class gr_ctx(flint_ctx):
         gr_vec_clear(gens, self.ctx_t)
         return py_gens
 
+    @cython.final
+    cdef inline truth_t _is_zero(self, gr x):
+        return gr_is_zero(x.pval, self.ctx_t)
+
+    @cython.final
+    cdef inline truth_t _is_one(self, gr x):
+        return gr_is_one(x.pval, self.ctx_t)
+
+    @cython.final
+    cdef inline truth_t _is_neg_one(self, gr x):
+        return gr_is_neg_one(x.pval, self.ctx_t)
+
     # @cython.final
     # cdef inline list _gens_recursive(self):
     #     cdef int err

src/flint/types/_gr.pyx

@@ -355,6 +355,48 @@ cdef class gr_ctx(flint_ctx):
         """
         return self._gens()
 
+    def is_zero(self, x) -> bool | None:
+        """
+        Returns whether x is equal to the ring element 0.
+
+            >>> from flint.types._gr import gr_real_arb_ctx
+            >>> ctx = gr_real_arb_ctx.new(10)
+            >>> ctx.is_zero(ctx(0))
+            True
+            >>> ctx.is_zero(ctx(1))
+            False
+            >>> ctx.is_zero(ctx("[0 +/- 0.1]"))
+        """
+        return truth_to_py(self._is_zero(x))
+
+    def is_one(self, x) -> bool | None:
+        """
+        Returns whether x is equal to the ring element 1.
+
+            >>> from flint.types._gr import gr_real_arb_ctx
+            >>> ctx = gr_real_arb_ctx.new(10)
+            >>> ctx.is_one(ctx(0))
+            False
+            >>> ctx.is_one(ctx(1))
+            True
+            >>> ctx.is_one(ctx("[1 +/- 0.1]"))
+        """
+        return truth_to_py(self._is_one(x))
+
+    def is_neg_one(self, x) -> bool | None:
+        """
+        Returns whether x is equal to the ring element -1.
+
+            >>> from flint.types._gr import gr_real_arb_ctx
+            >>> ctx = gr_real_arb_ctx.new(10)
+            >>> ctx.is_neg_one(ctx(1))
+            False
+            >>> ctx.is_neg_one(ctx(-1))
+            True
+            >>> ctx.is_neg_one(ctx("[-1 +/- 0.1]"))
+        """
+        return truth_to_py(self._is_neg_one(x))
+
     # def gens_recursive(self) -> list[gr]:
     #     """Return all generators of the domain