Function peekNextTokenType [src]
Seeks ahead in the input until the first byte of the next token (or the end of the input)
determines which type of token will be returned from the next next*() call.
This function is idempotent, only advancing past commas, colons, and inter-token whitespace.
Prototype
pub fn peekNextTokenType(self: *@This()) PeekError!TokenType Parameters
self: *@This() Possible Errors
Source
pub fn peekNextTokenType(self: *@This()) PeekError!TokenType {
state_loop: while (true) {
switch (self.state) {
.value => {
switch (try self.skipWhitespaceExpectByte()) {
'{' => return .object_begin,
'[' => return .array_begin,
'"' => return .string,
'-', '0'...'9' => return .number,
't' => return .true,
'f' => return .false,
'n' => return .null,
else => return error.SyntaxError,
}
},
.post_value => {
if (try self.skipWhitespaceCheckEnd()) return .end_of_document;
const c = self.input[self.cursor];
if (self.string_is_object_key) {
self.string_is_object_key = false;
switch (c) {
':' => {
self.cursor += 1;
self.state = .value;
continue :state_loop;
},
else => return error.SyntaxError,
}
}
switch (c) {
'}' => return .object_end,
']' => return .array_end,
',' => {
switch (self.stack.peek()) {
OBJECT_MODE => {
self.state = .object_post_comma;
},
ARRAY_MODE => {
self.state = .value;
},
}
self.cursor += 1;
continue :state_loop;
},
else => return error.SyntaxError,
}
},
.object_start => {
switch (try self.skipWhitespaceExpectByte()) {
'"' => return .string,
'}' => return .object_end,
else => return error.SyntaxError,
}
},
.object_post_comma => {
switch (try self.skipWhitespaceExpectByte()) {
'"' => return .string,
else => return error.SyntaxError,
}
},
.array_start => {
switch (try self.skipWhitespaceExpectByte()) {
']' => return .array_end,
else => {
self.state = .value;
continue :state_loop;
},
}
},
.number_minus,
.number_leading_zero,
.number_int,
.number_post_dot,
.number_frac,
.number_post_e,
.number_post_e_sign,
.number_exp,
=> return .number,
.string,
.string_backslash,
.string_backslash_u,
.string_backslash_u_1,
.string_backslash_u_2,
.string_backslash_u_3,
.string_surrogate_half,
.string_surrogate_half_backslash,
.string_surrogate_half_backslash_u,
.string_surrogate_half_backslash_u_1,
.string_surrogate_half_backslash_u_2,
.string_surrogate_half_backslash_u_3,
=> return .string,
.string_utf8_last_byte,
.string_utf8_second_to_last_byte,
.string_utf8_second_to_last_byte_guard_against_overlong,
.string_utf8_second_to_last_byte_guard_against_surrogate_half,
.string_utf8_third_to_last_byte,
.string_utf8_third_to_last_byte_guard_against_overlong,
.string_utf8_third_to_last_byte_guard_against_too_large,
=> return .string,
.literal_t,
.literal_tr,
.literal_tru,
=> return .true,
.literal_f,
.literal_fa,
.literal_fal,
.literal_fals,
=> return .false,
.literal_n,
.literal_nu,
.literal_nul,
=> return .null,
}
unreachable;
}
}