diff options
Diffstat (limited to 'Parser/string_parser.c')
| -rw-r--r-- | Parser/string_parser.c | 1421 |
1 files changed, 1421 insertions, 0 deletions
diff --git a/Parser/string_parser.c b/Parser/string_parser.c new file mode 100644 index 0000000..cb2332b --- /dev/null +++ b/Parser/string_parser.c @@ -0,0 +1,1421 @@ +#include <Python.h> + +#include "tokenizer.h" +#include "pegen.h" +#include "string_parser.h" + +//// STRING HANDLING FUNCTIONS //// + +// These functions are ported directly from Python/ast.c with some modifications +// to account for the use of "Parser *p", the fact that don't have parser nodes +// to pass around and the usage of some specialized APIs present only in this +// file (like "_PyPegen_raise_syntax_error"). + +static int +warn_invalid_escape_sequence(Parser *p, unsigned char first_invalid_escape_char, Token *t) +{ + PyObject *msg = + PyUnicode_FromFormat("invalid escape sequence \\%c", first_invalid_escape_char); + if (msg == NULL) { + return -1; + } + if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg, p->tok->filename, + t->lineno, NULL, NULL) < 0) { + if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) { + /* Replace the DeprecationWarning exception with a SyntaxError + to get a more accurate error report */ + PyErr_Clear(); + + /* This is needed, in order for the SyntaxError to point to the token t, + since _PyPegen_raise_error uses p->tokens[p->fill - 1] for the + error location, if p->known_err_token is not set. */ + p->known_err_token = t; + RAISE_SYNTAX_ERROR("invalid escape sequence \\%c", first_invalid_escape_char); + } + Py_DECREF(msg); + return -1; + } + Py_DECREF(msg); + return 0; +} + +static PyObject * +decode_utf8(const char **sPtr, const char *end) +{ + const char *s, *t; + t = s = *sPtr; + while (s < end && (*s & 0x80)) { + s++; + } + *sPtr = s; + return PyUnicode_DecodeUTF8(t, s - t, NULL); +} + +static PyObject * +decode_unicode_with_escapes(Parser *parser, const char *s, size_t len, Token *t) +{ + PyObject *v, *u; + char *buf; + char *p; + const char *end; + + /* check for integer overflow */ + if (len > SIZE_MAX / 6) { + return NULL; + } + /* "ä" (2 bytes) may become "\U000000E4" (10 bytes), or 1:5 + "\ä" (3 bytes) may become "\u005c\U000000E4" (16 bytes), or ~1:6 */ + u = PyBytes_FromStringAndSize((char *)NULL, len * 6); + if (u == NULL) { + return NULL; + } + p = buf = PyBytes_AsString(u); + end = s + len; + while (s < end) { + if (*s == '\\') { + *p++ = *s++; + if (s >= end || *s & 0x80) { + strcpy(p, "u005c"); + p += 5; + if (s >= end) { + break; + } + } + } + if (*s & 0x80) { + PyObject *w; + int kind; + void *data; + Py_ssize_t len, i; + w = decode_utf8(&s, end); + if (w == NULL) { + Py_DECREF(u); + return NULL; + } + kind = PyUnicode_KIND(w); + data = PyUnicode_DATA(w); + len = PyUnicode_GET_LENGTH(w); + for (i = 0; i < len; i++) { + Py_UCS4 chr = PyUnicode_READ(kind, data, i); + sprintf(p, "\\U%08x", chr); + p += 10; + } + /* Should be impossible to overflow */ + assert(p - buf <= PyBytes_GET_SIZE(u)); + Py_DECREF(w); + } + else { + *p++ = *s++; + } + } + len = p - buf; + s = buf; + + const char *first_invalid_escape; + v = _PyUnicode_DecodeUnicodeEscape(s, len, NULL, &first_invalid_escape); + + if (v != NULL && first_invalid_escape != NULL) { + if (warn_invalid_escape_sequence(parser, *first_invalid_escape, t) < 0) { + /* We have not decref u before because first_invalid_escape points + inside u. */ + Py_XDECREF(u); + Py_DECREF(v); + return NULL; + } + } + Py_XDECREF(u); + return v; +} + +static PyObject * +decode_bytes_with_escapes(Parser *p, const char *s, Py_ssize_t len, Token *t) +{ + const char *first_invalid_escape; + PyObject *result = _PyBytes_DecodeEscape(s, len, NULL, &first_invalid_escape); + if (result == NULL) { + return NULL; + } + + if (first_invalid_escape != NULL) { + if (warn_invalid_escape_sequence(p, *first_invalid_escape, t) < 0) { + Py_DECREF(result); + return NULL; + } + } + return result; +} + +/* s must include the bracketing quote characters, and r, b, u, + &/or f prefixes (if any), and embedded escape sequences (if any). + _PyPegen_parsestr parses it, and sets *result to decoded Python string object. + If the string is an f-string, set *fstr and *fstrlen to the unparsed + string object. Return 0 if no errors occurred. */ +int +_PyPegen_parsestr(Parser *p, int *bytesmode, int *rawmode, PyObject **result, + const char **fstr, Py_ssize_t *fstrlen, Token *t) +{ + const char *s = PyBytes_AsString(t->bytes); + if (s == NULL) { + return -1; + } + + size_t len; + int quote = Py_CHARMASK(*s); + int fmode = 0; + *bytesmode = 0; + *rawmode = 0; + *result = NULL; + *fstr = NULL; + if (Py_ISALPHA(quote)) { + while (!*bytesmode || !*rawmode) { + if (quote == 'b' || quote == 'B') { + quote = *++s; + *bytesmode = 1; + } + else if (quote == 'u' || quote == 'U') { + quote = *++s; + } + else if (quote == 'r' || quote == 'R') { + quote = *++s; + *rawmode = 1; + } + else if (quote == 'f' || quote == 'F') { + quote = *++s; + fmode = 1; + } + else { + break; + } + } + } + + /* fstrings are only allowed in Python 3.6 and greater */ + if (fmode && p->feature_version < 6) { + p->error_indicator = 1; + RAISE_SYNTAX_ERROR("Format strings are only supported in Python 3.6 and greater"); + return -1; + } + + if (fmode && *bytesmode) { + PyErr_BadInternalCall(); + return -1; + } + if (quote != '\'' && quote != '\"') { + PyErr_BadInternalCall(); + return -1; + } + /* Skip the leading quote char. */ + s++; + len = strlen(s); + if (len > INT_MAX) { + PyErr_SetString(PyExc_OverflowError, "string to parse is too long"); + return -1; + } + if (s[--len] != quote) { + /* Last quote char must match the first. */ + PyErr_BadInternalCall(); + return -1; + } + if (len >= 4 && s[0] == quote && s[1] == quote) { + /* A triple quoted string. We've already skipped one quote at + the start and one at the end of the string. Now skip the + two at the start. */ + s += 2; + len -= 2; + /* And check that the last two match. */ + if (s[--len] != quote || s[--len] != quote) { + PyErr_BadInternalCall(); + return -1; + } + } + + if (fmode) { + /* Just return the bytes. The caller will parse the resulting + string. */ + *fstr = s; + *fstrlen = len; + return 0; + } + + /* Not an f-string. */ + /* Avoid invoking escape decoding routines if possible. */ + *rawmode = *rawmode || strchr(s, '\\') == NULL; + if (*bytesmode) { + /* Disallow non-ASCII characters. */ + const char *ch; + for (ch = s; *ch; ch++) { + if (Py_CHARMASK(*ch) >= 0x80) { + RAISE_SYNTAX_ERROR( + "bytes can only contain ASCII " + "literal characters."); + return -1; + } + } + if (*rawmode) { + *result = PyBytes_FromStringAndSize(s, len); + } + else { + *result = decode_bytes_with_escapes(p, s, len, t); + } + } + else { + if (*rawmode) { + *result = PyUnicode_DecodeUTF8Stateful(s, len, NULL, NULL); + } + else { + *result = decode_unicode_with_escapes(p, s, len, t); + } + } + return *result == NULL ? -1 : 0; +} + + + +// FSTRING STUFF + +static void fstring_shift_expr_locations(expr_ty n, int lineno, int col_offset); +static void fstring_shift_argument(expr_ty parent, arg_ty args, int lineno, int col_offset); + + +static inline void shift_expr(expr_ty parent, expr_ty n, int line, int col) { + if (n == NULL) { + return; + } + if (parent->lineno < n->lineno) { + col = 0; + } + fstring_shift_expr_locations(n, line, col); +} + +static inline void shift_arg(expr_ty parent, arg_ty n, int line, int col) { + if (parent->lineno < n->lineno) { + col = 0; + } + fstring_shift_argument(parent, n, line, col); +} + +static void fstring_shift_seq_locations(expr_ty parent, asdl_seq *seq, int lineno, int col_offset) { + for (Py_ssize_t i = 0, l = asdl_seq_LEN(seq); i < l; i++) { + expr_ty expr = asdl_seq_GET(seq, i); + if (expr == NULL){ + continue; + } + shift_expr(parent, expr, lineno, col_offset); + } +} + +static void fstring_shift_slice_locations(expr_ty parent, expr_ty slice, int lineno, int col_offset) { + switch (slice->kind) { + case Slice_kind: + if (slice->v.Slice.lower) { + shift_expr(parent, slice->v.Slice.lower, lineno, col_offset); + } + if (slice->v.Slice.upper) { + shift_expr(parent, slice->v.Slice.upper, lineno, col_offset); + } + if (slice->v.Slice.step) { + shift_expr(parent, slice->v.Slice.step, lineno, col_offset); + } + break; + case Tuple_kind: + fstring_shift_seq_locations(parent, slice->v.Tuple.elts, lineno, col_offset); + break; + default: + break; + } +} + +static void fstring_shift_comprehension(expr_ty parent, comprehension_ty comp, int lineno, int col_offset) { + shift_expr(parent, comp->target, lineno, col_offset); + shift_expr(parent, comp->iter, lineno, col_offset); + fstring_shift_seq_locations(parent, comp->ifs, lineno, col_offset); +} + +static void fstring_shift_argument(expr_ty parent, arg_ty arg, int lineno, int col_offset) { + if (arg->annotation != NULL){ + shift_expr(parent, arg->annotation, lineno, col_offset); + } + arg->col_offset = arg->col_offset + col_offset; + arg->end_col_offset = arg->end_col_offset + col_offset; + arg->lineno = arg->lineno + lineno; + arg->end_lineno = arg->end_lineno + lineno; +} + +static void fstring_shift_arguments(expr_ty parent, arguments_ty args, int lineno, int col_offset) { + for (Py_ssize_t i = 0, l = asdl_seq_LEN(args->posonlyargs); i < l; i++) { + arg_ty arg = asdl_seq_GET(args->posonlyargs, i); + shift_arg(parent, arg, lineno, col_offset); + } + + for (Py_ssize_t i = 0, l = asdl_seq_LEN(args->args); i < l; i++) { + arg_ty arg = asdl_seq_GET(args->args, i); + shift_arg(parent, arg, lineno, col_offset); + } + + if (args->vararg != NULL) { + shift_arg(parent, args->vararg, lineno, col_offset); + } + + for (Py_ssize_t i = 0, l = asdl_seq_LEN(args->kwonlyargs); i < l; i++) { + arg_ty arg = asdl_seq_GET(args->kwonlyargs, i); + shift_arg(parent, arg, lineno, col_offset); + } + + fstring_shift_seq_locations(parent, args->kw_defaults, lineno, col_offset); + + if (args->kwarg != NULL) { + shift_arg(parent, args->kwarg, lineno, col_offset); + } + + fstring_shift_seq_locations(parent, args->defaults, lineno, col_offset); +} + +static void fstring_shift_children_locations(expr_ty n, int lineno, int col_offset) { + switch (n->kind) { + case BoolOp_kind: + fstring_shift_seq_locations(n, n->v.BoolOp.values, lineno, col_offset); + break; + case NamedExpr_kind: + shift_expr(n, n->v.NamedExpr.target, lineno, col_offset); + shift_expr(n, n->v.NamedExpr.value, lineno, col_offset); + break; + case BinOp_kind: + shift_expr(n, n->v.BinOp.left, lineno, col_offset); + shift_expr(n, n->v.BinOp.right, lineno, col_offset); + break; + case UnaryOp_kind: + shift_expr(n, n->v.UnaryOp.operand, lineno, col_offset); + break; + case Lambda_kind: + fstring_shift_arguments(n, n->v.Lambda.args, lineno, col_offset); + shift_expr(n, n->v.Lambda.body, lineno, col_offset); + break; + case IfExp_kind: + shift_expr(n, n->v.IfExp.test, lineno, col_offset); + shift_expr(n, n->v.IfExp.body, lineno, col_offset); + shift_expr(n, n->v.IfExp.orelse, lineno, col_offset); + break; + case Dict_kind: + fstring_shift_seq_locations(n, n->v.Dict.keys, lineno, col_offset); + fstring_shift_seq_locations(n, n->v.Dict.values, lineno, col_offset); + break; + case Set_kind: + fstring_shift_seq_locations(n, n->v.Set.elts, lineno, col_offset); + break; + case ListComp_kind: + shift_expr(n, n->v.ListComp.elt, lineno, col_offset); + for (Py_ssize_t i = 0, l = asdl_seq_LEN(n->v.ListComp.generators); i < l; i++) { + comprehension_ty comp = asdl_seq_GET(n->v.ListComp.generators, i); + fstring_shift_comprehension(n, comp, lineno, col_offset); + } + break; + case SetComp_kind: + shift_expr(n, n->v.SetComp.elt, lineno, col_offset); + for (Py_ssize_t i = 0, l = asdl_seq_LEN(n->v.SetComp.generators); i < l; i++) { + comprehension_ty comp = asdl_seq_GET(n->v.SetComp.generators, i); + fstring_shift_comprehension(n, comp, lineno, col_offset); + } + break; + case DictComp_kind: + shift_expr(n, n->v.DictComp.key, lineno, col_offset); + shift_expr(n, n->v.DictComp.value, lineno, col_offset); + for (Py_ssize_t i = 0, l = asdl_seq_LEN(n->v.DictComp.generators); i < l; i++) { + comprehension_ty comp = asdl_seq_GET(n->v.DictComp.generators, i); + fstring_shift_comprehension(n, comp, lineno, col_offset); + } + break; + case GeneratorExp_kind: + shift_expr(n, n->v.GeneratorExp.elt, lineno, col_offset); + for (Py_ssize_t i = 0, l = asdl_seq_LEN(n->v.GeneratorExp.generators); i < l; i++) { + comprehension_ty comp = asdl_seq_GET(n->v.GeneratorExp.generators, i); + fstring_shift_comprehension(n, comp, lineno, col_offset); + } + break; + case Await_kind: + shift_expr(n, n->v.Await.value, lineno, col_offset); + break; + case Yield_kind: + shift_expr(n, n->v.Yield.value, lineno, col_offset); + break; + case YieldFrom_kind: + shift_expr(n, n->v.YieldFrom.value, lineno, col_offset); + break; + case Compare_kind: + shift_expr(n, n->v.Compare.left, lineno, col_offset); + fstring_shift_seq_locations(n, n->v.Compare.comparators, lineno, col_offset); + break; + case Call_kind: + shift_expr(n, n->v.Call.func, lineno, col_offset); + fstring_shift_seq_locations(n, n->v.Call.args, lineno, col_offset); + for (Py_ssize_t i = 0, l = asdl_seq_LEN(n->v.Call.keywords); i < l; i++) { + keyword_ty keyword = asdl_seq_GET(n->v.Call.keywords, i); + shift_expr(n, keyword->value, lineno, col_offset); + } + break; + case Attribute_kind: + shift_expr(n, n->v.Attribute.value, lineno, col_offset); + break; + case Subscript_kind: + shift_expr(n, n->v.Subscript.value, lineno, col_offset); + fstring_shift_slice_locations(n, n->v.Subscript.slice, lineno, col_offset); + shift_expr(n, n->v.Subscript.slice, lineno, col_offset); + break; + case Starred_kind: + shift_expr(n, n->v.Starred.value, lineno, col_offset); + break; + case List_kind: + fstring_shift_seq_locations(n, n->v.List.elts, lineno, col_offset); + break; + case Tuple_kind: + fstring_shift_seq_locations(n, n->v.Tuple.elts, lineno, col_offset); + break; + case JoinedStr_kind: + fstring_shift_seq_locations(n, n->v.JoinedStr.values, lineno, col_offset); + break; + case FormattedValue_kind: + shift_expr(n, n->v.FormattedValue.value, lineno, col_offset); + if (n->v.FormattedValue.format_spec) { + shift_expr(n, n->v.FormattedValue.format_spec, lineno, col_offset); + } + break; + default: + return; + } +} + +/* Shift locations for the given node and all its children by adding `lineno` + and `col_offset` to existing locations. Note that n is the already parsed + expression. */ +static void fstring_shift_expr_locations(expr_ty n, int lineno, int col_offset) +{ + n->col_offset = n->col_offset + col_offset; + + // The following is needed, in order for nodes spanning across multiple lines + // to be shifted correctly. An example of such a node is a Call node, the closing + // parenthesis of which is not on the same line as its name. + if (n->lineno == n->end_lineno) { + n->end_col_offset = n->end_col_offset + col_offset; + } + + fstring_shift_children_locations(n, lineno, col_offset); + n->lineno = n->lineno + lineno; + n->end_lineno = n->end_lineno + lineno; +} + +/* Fix locations for the given node and its children. + + `parent` is the enclosing node. + `n` is the node which locations are going to be fixed relative to parent. + `expr_str` is the child node's string representation, including braces. +*/ +static void +fstring_fix_expr_location(Token *parent, expr_ty n, char *expr_str) +{ + char *substr = NULL; + char *start; + int lines = 0; + int cols = 0; + + if (parent && parent->bytes) { + char *parent_str = PyBytes_AsString(parent->bytes); + if (!parent_str) { + return; + } + substr = strstr(parent_str, expr_str); + if (substr) { + // The following is needed, in order to correctly shift the column + // offset, in the case that (disregarding any whitespace) a newline + // immediately follows the opening curly brace of the fstring expression. + int newline_after_brace = 1; + start = substr + 1; + while (start && *start != '}' && *start != '\n') { + if (*start != ' ' && *start != '\t' && *start != '\f') { + newline_after_brace = 0; + break; + } + start++; + } + + // Account for the characters from the last newline character to our + // left until the beginning of substr. + if (!newline_after_brace) { + start = substr; + while (start > parent_str && *start != '\n') { + start--; + } + cols += (int)(substr - start); + } + /* adjust the start based on the number of newlines encountered + before the f-string expression */ + for (char* p = parent_str; p < substr; p++) { + if (*p == '\n') { + lines++; + } + } + } + } + fstring_shift_expr_locations(n, lines, cols); +} + + +/* Compile this expression in to an expr_ty. Add parens around the + expression, in order to allow leading spaces in the expression. */ +static expr_ty +fstring_compile_expr(Parser *p, const char *expr_start, const char *expr_end, + Token *t) +{ + expr_ty expr = NULL; + char *str; + Py_ssize_t len; + const char *s; + expr_ty result = NULL; + + assert(expr_end >= expr_start); + assert(*(expr_start-1) == '{'); + assert(*expr_end == '}' || *expr_end == '!' || *expr_end == ':' || + *expr_end == '='); + + /* If the substring is all whitespace, it's an error. We need to catch this + here, and not when we call PyParser_SimpleParseStringFlagsFilename, + because turning the expression '' in to '()' would go from being invalid + to valid. */ + for (s = expr_start; s != expr_end; s++) { + char c = *s; + /* The Python parser ignores only the following whitespace + characters (\r already is converted to \n). */ + if (!(c == ' ' || c == '\t' || c == '\n' || c == '\f')) { + break; + } + } + if (s == expr_end) { + RAISE_SYNTAX_ERROR("f-string: empty expression not allowed"); + return NULL; + } + + len = expr_end - expr_start; + /* Allocate 3 extra bytes: open paren, close paren, null byte. */ + str = PyMem_RawMalloc(len + 3); + if (str == NULL) { + PyErr_NoMemory(); + return NULL; + } + + str[0] = '('; + memcpy(str+1, expr_start, len); + str[len+1] = ')'; + str[len+2] = 0; + + struct tok_state* tok = PyTokenizer_FromString(str, 1); + if (tok == NULL) { + PyMem_RawFree(str); + return NULL; + } + Py_INCREF(p->tok->filename); + tok->filename = p->tok->filename; + + Parser *p2 = _PyPegen_Parser_New(tok, Py_fstring_input, p->flags, p->feature_version, + NULL, p->arena); + p2->starting_lineno = p->starting_lineno + p->tok->first_lineno - 1; + p2->starting_col_offset = p->tok->first_lineno == p->tok->lineno + ? p->starting_col_offset + t->col_offset : 0; + + expr = _PyPegen_run_parser(p2); + + if (expr == NULL) { + goto exit; + } + + /* Reuse str to find the correct column offset. */ + str[0] = '{'; + str[len+1] = '}'; + fstring_fix_expr_location(t, expr, str); + + result = expr; + +exit: + PyMem_RawFree(str); + _PyPegen_Parser_Free(p2); + PyTokenizer_Free(tok); + return result; +} + +/* Return -1 on error. + + Return 0 if we reached the end of the literal. + + Return 1 if we haven't reached the end of the literal, but we want + the caller to process the literal up to this point. Used for + doubled braces. +*/ +static int +fstring_find_literal(Parser *p, const char **str, const char *end, int raw, + PyObject **literal, int recurse_lvl, Token *t) +{ + /* Get any literal string. It ends when we hit an un-doubled left + brace (which isn't part of a unicode name escape such as + "\N{EULER CONSTANT}"), or the end of the string. */ + + const char *s = *str; + const char *literal_start = s; + int result = 0; + + assert(*literal == NULL); + while (s < end) { + char ch = *s++; + if (!raw && ch == '\\' && s < end) { + ch = *s++; + if (ch == 'N') { + if (s < end && *s++ == '{') { + while (s < end && *s++ != '}') { + } + continue; + } + break; + } + if (ch == '{' && warn_invalid_escape_sequence(p, ch, t) < 0) { + return -1; + } + } + if (ch == '{' || ch == '}') { + /* Check for doubled braces, but only at the top level. If + we checked at every level, then f'{0:{3}}' would fail + with the two closing braces. */ + if (recurse_lvl == 0) { + if (s < end && *s == ch) { + /* We're going to tell the caller that the literal ends + here, but that they should continue scanning. But also + skip over the second brace when we resume scanning. */ + *str = s + 1; + result = 1; + goto done; + } + + /* Where a single '{' is the start of a new expression, a + single '}' is not allowed. */ + if (ch == '}') { + *str = s - 1; + RAISE_SYNTAX_ERROR("f-string: single '}' is not allowed"); + return -1; + } + } + /* We're either at a '{', which means we're starting another + expression; or a '}', which means we're at the end of this + f-string (for a nested format_spec). */ + s--; + break; + } + } + *str = s; + assert(s <= end); + assert(s == end || *s == '{' || *s == '}'); +done: + if (literal_start != s) { + if (raw) + *literal = PyUnicode_DecodeUTF8Stateful(literal_start, + s - literal_start, + NULL, NULL); + else + *literal = decode_unicode_with_escapes(p, literal_start, + s - literal_start, t); + if (!*literal) + return -1; + } + return result; +} + +/* Forward declaration because parsing is recursive. */ +static expr_ty +fstring_parse(Parser *p, const char **str, const char *end, int raw, int recurse_lvl, + Token *first_token, Token* t, Token *last_token); + +/* Parse the f-string at *str, ending at end. We know *str starts an + expression (so it must be a '{'). Returns the FormattedValue node, which + includes the expression, conversion character, format_spec expression, and + optionally the text of the expression (if = is used). + + Note that I don't do a perfect job here: I don't make sure that a + closing brace doesn't match an opening paren, for example. It + doesn't need to error on all invalid expressions, just correctly + find the end of all valid ones. Any errors inside the expression + will be caught when we parse it later. + + *expression is set to the expression. For an '=' "debug" expression, + *expr_text is set to the debug text (the original text of the expression, + including the '=' and any whitespace around it, as a string object). If + not a debug expression, *expr_text set to NULL. */ +static int +fstring_find_expr(Parser *p, const char **str, const char *end, int raw, int recurse_lvl, + PyObject **expr_text, expr_ty *expression, Token *first_token, + Token *t, Token *last_token) +{ + /* Return -1 on error, else 0. */ + + const char *expr_start; + const char *expr_end; + expr_ty simple_expression; + expr_ty format_spec = NULL; /* Optional format specifier. */ + int conversion = -1; /* The conversion char. Use default if not + specified, or !r if using = and no format + spec. */ + + /* 0 if we're not in a string, else the quote char we're trying to + match (single or double quote). */ + char quote_char = 0; + + /* If we're inside a string, 1=normal, 3=triple-quoted. */ + int string_type = 0; + + /* Keep track of nesting level for braces/parens/brackets in + expressions. */ + Py_ssize_t nested_depth = 0; + char parenstack[MAXLEVEL]; + + *expr_text = NULL; + + /* Can only nest one level deep. */ + if (recurse_lvl >= 2) { + RAISE_SYNTAX_ERROR("f-string: expressions nested too deeply"); + goto error; + } + + /* The first char must be a left brace, or we wouldn't have gotten + here. Skip over it. */ + assert(**str == '{'); + *str += 1; + + expr_start = *str; + for (; *str < end; (*str)++) { + char ch; + + /* Loop invariants. */ + assert(nested_depth >= 0); + assert(*str >= expr_start && *str < end); + if (quote_char) + assert(string_type == 1 || string_type == 3); + else + assert(string_type == 0); + + ch = **str; + /* Nowhere inside an expression is a backslash allowed. */ + if (ch == '\\') { + /* Error: can't include a backslash character, inside + parens or strings or not. */ + RAISE_SYNTAX_ERROR( + "f-string expression part " + "cannot include a backslash"); + goto error; + } + if (quote_char) { + /* We're inside a string. See if we're at the end. */ + /* This code needs to implement the same non-error logic + as tok_get from tokenizer.c, at the letter_quote + label. To actually share that code would be a + nightmare. But, it's unlikely to change and is small, + so duplicate it here. Note we don't need to catch all + of the errors, since they'll be caught when parsing the + expression. We just need to match the non-error + cases. Thus we can ignore \n in single-quoted strings, + for example. Or non-terminated strings. */ + if (ch == quote_char) { + /* Does this match the string_type (single or triple + quoted)? */ + if (string_type == 3) { + if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) { + /* We're at the end of a triple quoted string. */ + *str += 2; + string_type = 0; + quote_char = 0; + continue; + } + } else { + /* We're at the end of a normal string. */ + quote_char = 0; + string_type = 0; + continue; + } + } + } else if (ch == '\'' || ch == '"') { + /* Is this a triple quoted string? */ + if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) { + string_type = 3; + *str += 2; + } else { + /* Start of a normal string. */ + string_type = 1; + } + /* Start looking for the end of the string. */ + quote_char = ch; + } else if (ch == '[' || ch == '{' || ch == '(') { + if (nested_depth >= MAXLEVEL) { + RAISE_SYNTAX_ERROR("f-string: too many nested parenthesis"); + goto error; + } + parenstack[nested_depth] = ch; + nested_depth++; + } else if (ch == '#') { + /* Error: can't include a comment character, inside parens + or not. */ + RAISE_SYNTAX_ERROR("f-string expression part cannot include '#'"); + goto error; + } else if (nested_depth == 0 && + (ch == '!' || ch == ':' || ch == '}' || + ch == '=' || ch == '>' || ch == '<')) { + /* See if there's a next character. */ + if (*str+1 < end) { + char next = *(*str+1); + + /* For "!=". since '=' is not an allowed conversion character, + nothing is lost in this test. */ + if ((ch == '!' && next == '=') || /* != */ + (ch == '=' && next == '=') || /* == */ + (ch == '<' && next == '=') || /* <= */ + (ch == '>' && next == '=') /* >= */ + ) { + *str += 1; + continue; + } + /* Don't get out of the loop for these, if they're single + chars (not part of 2-char tokens). If by themselves, they + don't end an expression (unlike say '!'). */ + if (ch == '>' || ch == '<') { + continue; + } + } + + /* Normal way out of this loop. */ + break; + } else if (ch == ']' || ch == '}' || ch == ')') { + if (!nested_depth) { + RAISE_SYNTAX_ERROR("f-string: unmatched '%c'", ch); + goto error; + } + nested_depth--; + int opening = parenstack[nested_depth]; + if (!((opening == '(' && ch == ')') || + (opening == '[' && ch == ']') || + (opening == '{' && ch == '}'))) + { + RAISE_SYNTAX_ERROR( + "f-string: closing parenthesis '%c' " + "does not match opening parenthesis '%c'", + ch, opening); + goto error; + } + } else { + /* Just consume this char and loop around. */ + } + } + expr_end = *str; + /* If we leave this loop in a string or with mismatched parens, we + don't care. We'll get a syntax error when compiling the + expression. But, we can produce a better error message, so + let's just do that.*/ + if (quote_char) { + RAISE_SYNTAX_ERROR("f-string: unterminated string"); + goto error; + } + if (nested_depth) { + int opening = parenstack[nested_depth - 1]; + RAISE_SYNTAX_ERROR("f-string: unmatched '%c'", opening); + goto error; + } + + if (*str >= end) + goto unexpected_end_of_string; + + /* Compile the expression as soon as possible, so we show errors + related to the expression before errors related to the + conversion or format_spec. */ + simple_expression = fstring_compile_expr(p, expr_start, expr_end, t); + if (!simple_expression) + goto error; + + /* Check for =, which puts the text value of the expression in + expr_text. */ + if (**str == '=') { + if (p->feature_version < 8) { + RAISE_SYNTAX_ERROR("f-string: self documenting expressions are " + "only supported in Python 3.8 and greater"); + goto error; + } + *str += 1; + + /* Skip over ASCII whitespace. No need to test for end of string + here, since we know there's at least a trailing quote somewhere + ahead. */ + while (Py_ISSPACE(**str)) { + *str += 1; + } + + /* Set *expr_text to the text of the expression. */ + *expr_text = PyUnicode_FromStringAndSize(expr_start, *str-expr_start); + if (!*expr_text) { + goto error; + } + } + + /* Check for a conversion char, if present. */ + if (**str == '!') { + *str += 1; + if (*str >= end) + goto unexpected_end_of_string; + + conversion = **str; + *str += 1; + + /* Validate the conversion. */ + if (!(conversion == 's' || conversion == 'r' || conversion == 'a')) { + RAISE_SYNTAX_ERROR( + "f-string: invalid conversion character: " + "expected 's', 'r', or 'a'"); + goto error; + } + + } + + /* Check for the format spec, if present. */ + if (*str >= end) + goto unexpected_end_of_string; + if (**str == ':') { + *str += 1; + if (*str >= end) + goto unexpected_end_of_string; + + /* Parse the format spec. */ + format_spec = fstring_parse(p, str, end, raw, recurse_lvl+1, + first_token, t, last_token); + if (!format_spec) + goto error; + } + + if (*str >= end || **str != '}') + goto unexpected_end_of_string; + + /* We're at a right brace. Consume it. */ + assert(*str < end); + assert(**str == '}'); + *str += 1; + + /* If we're in = mode (detected by non-NULL expr_text), and have no format + spec and no explicit conversion, set the conversion to 'r'. */ + if (*expr_text && format_spec == NULL && conversion == -1) { + conversion = 'r'; + } + + /* And now create the FormattedValue node that represents this + entire expression with the conversion and format spec. */ + //TODO: Fix this + *expression = FormattedValue(simple_expression, conversion, + format_spec, first_token->lineno, + first_token->col_offset, last_token->end_lineno, + last_token->end_col_offset, p->arena); + if (!*expression) + goto error; + + return 0; + +unexpected_end_of_string: + RAISE_SYNTAX_ERROR("f-string: expecting '}'"); + /* Falls through to error. */ + +error: + Py_XDECREF(*expr_text); + return -1; + +} + +/* Return -1 on error. + + Return 0 if we have a literal (possible zero length) and an + expression (zero length if at the end of the string. + + Return 1 if we have a literal, but no expression, and we want the + caller to call us again. This is used to deal with doubled + braces. + + When called multiple times on the string 'a{{b{0}c', this function + will return: + + 1. the literal 'a{' with no expression, and a return value + of 1. Despite the fact that there's no expression, the return + value of 1 means we're not finished yet. + + 2. the literal 'b' and the expression '0', with a return value of + 0. The fact that there's an expression means we're not finished. + + 3. literal 'c' with no expression and a return value of 0. The + combination of the return value of 0 with no expression means + we're finished. +*/ +static int +fstring_find_literal_and_expr(Parser *p, const char **str, const char *end, int raw, + int recurse_lvl, PyObject **literal, + PyObject **expr_text, expr_ty *expression, + Token *first_token, Token *t, Token *last_token) +{ + int result; + + assert(*literal == NULL && *expression == NULL); + + /* Get any literal string. */ + result = fstring_find_literal(p, str, end, raw, literal, recurse_lvl, t); + if (result < 0) + goto error; + + assert(result == 0 || result == 1); + + if (result == 1) + /* We have a literal, but don't look at the expression. */ + return 1; + + if (*str >= end || **str == '}') + /* We're at the end of the string or the end of a nested + f-string: no expression. The top-level error case where we + expect to be at the end of the string but we're at a '}' is + handled later. */ + return 0; + + /* We must now be the start of an expression, on a '{'. */ + assert(**str == '{'); + + if (fstring_find_expr(p, str, end, raw, recurse_lvl, expr_text, + expression, first_token, t, last_token) < 0) + goto error; + + return 0; + +error: + Py_CLEAR(*literal); + return -1; +} + +#ifdef NDEBUG +#define ExprList_check_invariants(l) +#else +static void +ExprList_check_invariants(ExprList *l) +{ + /* Check our invariants. Make sure this object is "live", and + hasn't been deallocated. */ + assert(l->size >= 0); + assert(l->p != NULL); + if (l->size <= EXPRLIST_N_CACHED) + assert(l->data == l->p); +} +#endif + +static void +ExprList_Init(ExprList *l) +{ + l->allocated = EXPRLIST_N_CACHED; + l->size = 0; + + /* Until we start allocating dynamically, p points to data. */ + l->p = l->data; + + ExprList_check_invariants(l); +} + +static int +ExprList_Append(ExprList *l, expr_ty exp) +{ + ExprList_check_invariants(l); + if (l->size >= l->allocated) { + /* We need to alloc (or realloc) the memory. */ + Py_ssize_t new_size = l->allocated * 2; + + /* See if we've ever allocated anything dynamically. */ + if (l->p == l->data) { + Py_ssize_t i; + /* We're still using the cached data. Switch to + alloc-ing. */ + l->p = PyMem_RawMalloc(sizeof(expr_ty) * new_size); + if (!l->p) + return -1; + /* Copy the cached data into the new buffer. */ + for (i = 0; i < l->size; i++) + l->p[i] = l->data[i]; + } else { + /* Just realloc. */ + expr_ty *tmp = PyMem_RawRealloc(l->p, sizeof(expr_ty) * new_size); + if (!tmp) { + PyMem_RawFree(l->p); + l->p = NULL; + return -1; + } + l->p = tmp; + } + + l->allocated = new_size; + assert(l->allocated == 2 * l->size); + } + + l->p[l->size++] = exp; + + ExprList_check_invariants(l); + return 0; +} + +static void +ExprList_Dealloc(ExprList *l) +{ + ExprList_check_invariants(l); + + /* If there's been an error, or we've never dynamically allocated, + do nothing. */ + if (!l->p || l->p == l->data) { + /* Do nothing. */ + } else { + /* We have dynamically allocated. Free the memory. */ + PyMem_RawFree(l->p); + } + l->p = NULL; + l->size = -1; +} + +static asdl_seq * +ExprList_Finish(ExprList *l, PyArena *arena) +{ + asdl_seq *seq; + + ExprList_check_invariants(l); + + /* Allocate the asdl_seq and copy the expressions in to it. */ + seq = _Py_asdl_seq_new(l->size, arena); + if (seq) { + Py_ssize_t i; + for (i = 0; i < l->size; i++) + asdl_seq_SET(seq, i, l->p[i]); + } + ExprList_Dealloc(l); + return seq; +} + +#ifdef NDEBUG +#define FstringParser_check_invariants(state) +#else +static void +FstringParser_check_invariants(FstringParser *state) +{ + if (state->last_str) + assert(PyUnicode_CheckExact(state->last_str)); + ExprList_check_invariants(&state->expr_list); +} +#endif + +void +_PyPegen_FstringParser_Init(FstringParser *state) +{ + state->last_str = NULL; + state->fmode = 0; + ExprList_Init(&state->expr_list); + FstringParser_check_invariants(state); +} + +void +_PyPegen_FstringParser_Dealloc(FstringParser *state) +{ + FstringParser_check_invariants(state); + + Py_XDECREF(state->last_str); + ExprList_Dealloc(&state->expr_list); +} + +/* Make a Constant node, but decref the PyUnicode object being added. */ +static expr_ty +make_str_node_and_del(Parser *p, PyObject **str, Token* first_token, Token *last_token) +{ + PyObject *s = *str; + PyObject *kind = NULL; + *str = NULL; + assert(PyUnicode_CheckExact(s)); + if (PyArena_AddPyObject(p->arena, s) < 0) { + Py_DECREF(s); + return NULL; + } + const char* the_str = PyBytes_AsString(first_token->bytes); + if (the_str && the_str[0] == 'u') { + kind = _PyPegen_new_identifier(p, "u"); + } + + if (kind == NULL && PyErr_Occurred()) { + return NULL; + } + + return Constant(s, kind, first_token->lineno, first_token->col_offset, + last_token->end_lineno, last_token->end_col_offset, p->arena); + +} + + +/* Add a non-f-string (that is, a regular literal string). str is + decref'd. */ +int +_PyPegen_FstringParser_ConcatAndDel(FstringParser *state, PyObject *str) +{ + FstringParser_check_invariants(state); + + assert(PyUnicode_CheckExact(str)); + + if (PyUnicode_GET_LENGTH(str) == 0) { + Py_DECREF(str); + return 0; + } + + if (!state->last_str) { + /* We didn't have a string before, so just remember this one. */ + state->last_str = str; + } else { + /* Concatenate this with the previous string. */ + PyUnicode_AppendAndDel(&state->last_str, str); + if (!state->last_str) + return -1; + } + FstringParser_check_invariants(state); + return 0; +} + +/* Parse an f-string. The f-string is in *str to end, with no + 'f' or quotes. */ +int +_PyPegen_FstringParser_ConcatFstring(Parser *p, FstringParser *state, const char **str, + const char *end, int raw, int recurse_lvl, + Token *first_token, Token* t, Token *last_token) +{ + FstringParser_check_invariants(state); + state->fmode = 1; + + /* Parse the f-string. */ + while (1) { + PyObject *literal = NULL; + PyObject *expr_text = NULL; + expr_ty expression = NULL; + + /* If there's a zero length literal in front of the + expression, literal will be NULL. If we're at the end of + the f-string, expression will be NULL (unless result == 1, + see below). */ + int result = fstring_find_literal_and_expr(p, str, end, raw, recurse_lvl, + &literal, &expr_text, + &expression, first_token, t, last_token); + if (result < 0) + return -1; + + /* Add the literal, if any. */ + if (literal && _PyPegen_FstringParser_ConcatAndDel(state, literal) < 0) { + Py_XDECREF(expr_text); + return -1; + } + /* Add the expr_text, if any. */ + if (expr_text && _PyPegen_FstringParser_ConcatAndDel(state, expr_text) < 0) { + return -1; + } + + /* We've dealt with the literal and expr_text, their ownership has + been transferred to the state object. Don't look at them again. */ + + /* See if we should just loop around to get the next literal + and expression, while ignoring the expression this + time. This is used for un-doubling braces, as an + optimization. */ + if (result == 1) + continue; + + if (!expression) + /* We're done with this f-string. */ + break; + + /* We know we have an expression. Convert any existing string + to a Constant node. */ + if (!state->last_str) { + /* Do nothing. No previous literal. */ + } else { + /* Convert the existing last_str literal to a Constant node. */ + expr_ty str = make_str_node_and_del(p, &state->last_str, first_token, last_token); + if (!str || ExprList_Append(&state->expr_list, str) < 0) + return -1; + } + + if (ExprList_Append(&state->expr_list, expression) < 0) + return -1; + } + + /* If recurse_lvl is zero, then we must be at the end of the + string. Otherwise, we must be at a right brace. */ + + if (recurse_lvl == 0 && *str < end-1) { + RAISE_SYNTAX_ERROR("f-string: unexpected end of string"); + return -1; + } + if (recurse_lvl != 0 && **str != '}') { + RAISE_SYNTAX_ERROR("f-string: expecting '}'"); + return -1; + } + + FstringParser_check_invariants(state); + return 0; +} + +/* Convert the partial state reflected in last_str and expr_list to an + expr_ty. The expr_ty can be a Constant, or a JoinedStr. */ +expr_ty +_PyPegen_FstringParser_Finish(Parser *p, FstringParser *state, Token* first_token, + Token *last_token) +{ + asdl_seq *seq; + + FstringParser_check_invariants(state); + + /* If we're just a constant string with no expressions, return + that. */ + if (!state->fmode) { + assert(!state->expr_list.size); + if (!state->last_str) { + /* Create a zero length string. */ + state->last_str = PyUnicode_FromStringAndSize(NULL, 0); + if (!state->last_str) + goto error; + } + return make_str_node_and_del(p, &state->last_str, first_token, last_token); + } + + /* Create a Constant node out of last_str, if needed. It will be the + last node in our expression list. */ + if (state->last_str) { + expr_ty str = make_str_node_and_del(p, &state->last_str, first_token, last_token); + if (!str || ExprList_Append(&state->expr_list, str) < 0) + goto error; + } + /* This has already been freed. */ + assert(state->last_str == NULL); + + seq = ExprList_Finish(&state->expr_list, p->arena); + if (!seq) + goto error; + + return _Py_JoinedStr(seq, first_token->lineno, first_token->col_offset, + last_token->end_lineno, last_token->end_col_offset, p->arena); + +error: + _PyPegen_FstringParser_Dealloc(state); + return NULL; +} + +/* Given an f-string (with no 'f' or quotes) that's in *str and ends + at end, parse it into an expr_ty. Return NULL on error. Adjust + str to point past the parsed portion. */ +static expr_ty +fstring_parse(Parser *p, const char **str, const char *end, int raw, + int recurse_lvl, Token *first_token, Token* t, Token *last_token) +{ + FstringParser state; + + _PyPegen_FstringParser_Init(&state); + if (_PyPegen_FstringParser_ConcatFstring(p, &state, str, end, raw, recurse_lvl, + first_token, t, last_token) < 0) { + _PyPegen_FstringParser_Dealloc(&state); + return NULL; + } + + return _PyPegen_FstringParser_Finish(p, &state, t, t); +} |