isl_multi_*_dim: use isl_multi_*_peek_space

[isl.git] / isl_stream.c

/*
 * Copyright 2008-2009 Katholieke Universiteit Leuven
 *
 * Use of this software is governed by the MIT license
 *
 * Written by Sven Verdoolaege, K.U.Leuven, Departement
 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
 */

#include <ctype.h>
#include <string.h>
#include <isl/ctx.h>
#include <isl_stream_private.h>
#include <isl/map.h>
#include <isl/aff.h>
#include <isl_val_private.h>

struct isl_keyword {
        char                    *name;
        enum isl_token_type     type;
};

static int same_name(const void *entry, const void *val)
{
        const struct isl_keyword *keyword = (const struct isl_keyword *)entry;

        return !strcmp(keyword->name, val);
}

enum isl_token_type isl_stream_register_keyword(__isl_keep isl_stream *s,
        const char *name)
{
        struct isl_hash_table_entry *entry;
        struct isl_keyword *keyword;
        uint32_t name_hash;

        if (!s->keywords) {
                s->keywords = isl_hash_table_alloc(s->ctx, 10);
                if (!s->keywords)
                        return ISL_TOKEN_ERROR;
                s->next_type = ISL_TOKEN_LAST;
        }

        name_hash = isl_hash_string(isl_hash_init(), name);

        entry = isl_hash_table_find(s->ctx, s->keywords, name_hash,
                                        same_name, name, 1);
        if (!entry)
                return ISL_TOKEN_ERROR;
        if (entry->data) {
                keyword = entry->data;
                return keyword->type;
        }

        keyword = isl_calloc_type(s->ctx, struct isl_keyword);
        if (!keyword)
                return ISL_TOKEN_ERROR;
        keyword->type = s->next_type++;
        keyword->name = strdup(name);
        if (!keyword->name) {
                free(keyword);
                return ISL_TOKEN_ERROR;
        }
        entry->data = keyword;

        return keyword->type;
}

struct isl_token *isl_token_new(isl_ctx *ctx,
        int line, int col, unsigned on_new_line)
{
        struct isl_token *tok = isl_alloc_type(ctx, struct isl_token);
        if (!tok)
                return NULL;
        tok->line = line;
        tok->col = col;
        tok->on_new_line = on_new_line;
        tok->is_keyword = 0;
        tok->u.s = NULL;
        return tok;
}

/* Return the type of "tok".
 */
int isl_token_get_type(struct isl_token *tok)
{
        return tok ? tok->type : ISL_TOKEN_ERROR;
}

/* Given a token of type ISL_TOKEN_VALUE, return the value it represents.
 */
__isl_give isl_val *isl_token_get_val(isl_ctx *ctx, struct isl_token *tok)
{
        if (!tok)
                return NULL;
        if (tok->type != ISL_TOKEN_VALUE)
                isl_die(ctx, isl_error_invalid, "not a value token",
                        return NULL);

        return isl_val_int_from_isl_int(ctx, tok->u.v);
}

/* Given a token with a string representation, return a copy of this string.
 */
__isl_give char *isl_token_get_str(isl_ctx *ctx, struct isl_token *tok)
{
        if (!tok)
                return NULL;
        if (!tok->u.s)
                isl_die(ctx, isl_error_invalid,
                        "token does not have a string representation",
                        return NULL);

        return strdup(tok->u.s);
}

void isl_token_free(struct isl_token *tok)
{
        if (!tok)
                return;
        if (tok->type == ISL_TOKEN_VALUE)
                isl_int_clear(tok->u.v);
        else if (tok->type == ISL_TOKEN_MAP)
                isl_map_free(tok->u.map);
        else if (tok->type == ISL_TOKEN_AFF)
                isl_pw_aff_free(tok->u.pwaff);
        else
                free(tok->u.s);
        free(tok);
}

void isl_stream_error(__isl_keep isl_stream *s, struct isl_token *tok,
        char *msg)
{
        int line = tok ? tok->line : s->line;
        int col = tok ? tok->col : s->col;
        fprintf(stderr, "syntax error (%d, %d): %s\n", line, col, msg);
        if (tok) {
                if (tok->type < 256)
                        fprintf(stderr, "got '%c'\n", tok->type);
                else if (tok->type == ISL_TOKEN_IDENT)
                        fprintf(stderr, "got ident '%s'\n", tok->u.s);
                else if (tok->is_keyword)
                        fprintf(stderr, "got keyword '%s'\n", tok->u.s);
                else if (tok->type == ISL_TOKEN_VALUE) {
                        fprintf(stderr, "got value '");
                        isl_int_print(stderr, tok->u.v, 0);
                        fprintf(stderr, "'\n");
                } else if (tok->type == ISL_TOKEN_MAP) {
                        isl_printer *p;
                        fprintf(stderr, "got map '");
                        p = isl_printer_to_file(s->ctx, stderr);
                        p = isl_printer_print_map(p, tok->u.map);
                        isl_printer_free(p);
                        fprintf(stderr, "'\n");
                } else if (tok->type == ISL_TOKEN_AFF) {
                        isl_printer *p;
                        fprintf(stderr, "got affine expression '");
                        p = isl_printer_to_file(s->ctx, stderr);
                        p = isl_printer_print_pw_aff(p, tok->u.pwaff);
                        isl_printer_free(p);
                        fprintf(stderr, "'\n");
                } else if (tok->u.s)
                        fprintf(stderr, "got token '%s'\n", tok->u.s);
                else
                        fprintf(stderr, "got token type %d\n", tok->type);
        }
}

static __isl_give isl_stream* isl_stream_new(struct isl_ctx *ctx)
{
        int i;
        isl_stream *s = isl_calloc_type(ctx, struct isl_stream);
        if (!s)
                return NULL;
        s->ctx = ctx;
        isl_ctx_ref(s->ctx);
        s->file = NULL;
        s->str = NULL;
        s->len = 0;
        s->line = 1;
        s->col = 1;
        s->eof = 0;
        s->last_line = 0;
        s->c = -1;
        s->n_un = 0;
        for (i = 0; i < 5; ++i)
                s->tokens[i] = NULL;
        s->n_token = 0;
        s->keywords = NULL;
        s->size = 256;
        s->buffer = isl_alloc_array(ctx, char, s->size);
        if (!s->buffer)
                goto error;
        return s;
error:
        isl_stream_free(s);
        return NULL;
}

__isl_give isl_stream* isl_stream_new_file(struct isl_ctx *ctx, FILE *file)
{
        isl_stream *s = isl_stream_new(ctx);
        if (!s)
                return NULL;
        s->file = file;
        return s;
}

__isl_give isl_stream* isl_stream_new_str(struct isl_ctx *ctx, const char *str)
{
        isl_stream *s;
        if (!str)
                return NULL;
        s = isl_stream_new(ctx);
        if (!s)
                return NULL;
        s->str = str;
        return s;
}

/* Read a character from the stream and advance s->line and s->col
 * to point to the next character.
 */
static int stream_getc(__isl_keep isl_stream *s)
{
        int c;
        if (s->eof)
                return -1;
        if (s->n_un)
                return s->c = s->un[--s->n_un];
        if (s->file)
                c = fgetc(s->file);
        else {
                c = *s->str++;
                if (c == '\0')
                        c = -1;
        }
        if (c == -1)
                s->eof = 1;
        else if (c == '\n') {
                s->line++;
                s->col = 1;
        } else
                s->col++;
        s->c = c;
        return c;
}

static void isl_stream_ungetc(__isl_keep isl_stream *s, int c)
{
        isl_assert(s->ctx, s->n_un < 5, return);
        s->un[s->n_un++] = c;
        s->c = -1;
}

/* Read a character from the stream, skipping pairs of '\\' and '\n'.
 * Set s->start_line and s->start_col to the line and column
 * of the returned character.
 */
static int isl_stream_getc(__isl_keep isl_stream *s)
{
        int c;

        do {
                s->start_line = s->line;
                s->start_col = s->col;
                c = stream_getc(s);
                if (c != '\\')
                        return c;
                c = stream_getc(s);
        } while (c == '\n');

        isl_stream_ungetc(s, c);

        return '\\';
}

static int isl_stream_push_char(__isl_keep isl_stream *s, int c)
{
        if (s->len >= s->size) {
                char *buffer;
                s->size = (3*s->size)/2;
                buffer = isl_realloc_array(s->ctx, s->buffer, char, s->size);
                if (!buffer)
                        return -1;
                s->buffer = buffer;
        }
        s->buffer[s->len++] = c;
        return 0;
}

void isl_stream_push_token(__isl_keep isl_stream *s, struct isl_token *tok)
{
        isl_assert(s->ctx, s->n_token < 5, return);
        s->tokens[s->n_token++] = tok;
}

static enum isl_token_type check_keywords(__isl_keep isl_stream *s)
{
        struct isl_hash_table_entry *entry;
        struct isl_keyword *keyword;
        uint32_t name_hash;

        if (!strcasecmp(s->buffer, "exists"))
                return ISL_TOKEN_EXISTS;
        if (!strcasecmp(s->buffer, "and"))
                return ISL_TOKEN_AND;
        if (!strcasecmp(s->buffer, "or"))
                return ISL_TOKEN_OR;
        if (!strcasecmp(s->buffer, "implies"))
                return ISL_TOKEN_IMPLIES;
        if (!strcasecmp(s->buffer, "not"))
                return ISL_TOKEN_NOT;
        if (!strcasecmp(s->buffer, "infty"))
                return ISL_TOKEN_INFTY;
        if (!strcasecmp(s->buffer, "infinity"))
                return ISL_TOKEN_INFTY;
        if (!strcasecmp(s->buffer, "NaN"))
                return ISL_TOKEN_NAN;
        if (!strcasecmp(s->buffer, "min"))
                return ISL_TOKEN_MIN;
        if (!strcasecmp(s->buffer, "max"))
                return ISL_TOKEN_MAX;
        if (!strcasecmp(s->buffer, "rat"))
                return ISL_TOKEN_RAT;
        if (!strcasecmp(s->buffer, "true"))
                return ISL_TOKEN_TRUE;
        if (!strcasecmp(s->buffer, "false"))
                return ISL_TOKEN_FALSE;
        if (!strcasecmp(s->buffer, "ceild"))
                return ISL_TOKEN_CEILD;
        if (!strcasecmp(s->buffer, "floord"))
                return ISL_TOKEN_FLOORD;
        if (!strcasecmp(s->buffer, "mod"))
                return ISL_TOKEN_MOD;
        if (!strcasecmp(s->buffer, "ceil"))
                return ISL_TOKEN_CEIL;
        if (!strcasecmp(s->buffer, "floor"))
                return ISL_TOKEN_FLOOR;

        if (!s->keywords)
                return ISL_TOKEN_IDENT;

        name_hash = isl_hash_string(isl_hash_init(), s->buffer);
        entry = isl_hash_table_find(s->ctx, s->keywords, name_hash, same_name,
                                        s->buffer, 0);
        if (entry) {
                keyword = entry->data;
                return keyword->type;
        }

        return ISL_TOKEN_IDENT;
}

int isl_stream_skip_line(__isl_keep isl_stream *s)
{
        int c;

        while ((c = isl_stream_getc(s)) != -1 && c != '\n')
                /* nothing */
                ;

        return c == -1 ? -1 : 0;
}

static struct isl_token *next_token(__isl_keep isl_stream *s, int same_line)
{
        int c;
        struct isl_token *tok = NULL;
        int line, col;
        int old_line = s->last_line;

        if (s->n_token) {
                if (same_line && s->tokens[s->n_token - 1]->on_new_line)
                        return NULL;
                return s->tokens[--s->n_token];
        }

        if (same_line && s->c == '\n')
                return NULL;

        s->len = 0;

        /* skip spaces and comment lines */
        while ((c = isl_stream_getc(s)) != -1) {
                if (c == '#') {
                        if (isl_stream_skip_line(s) < 0)
                                break;
                        c = '\n';
                        if (same_line)
                                break;
                } else if (!isspace(c) || (same_line && c == '\n'))
                        break;
        }

        line = s->start_line;
        col = s->start_col;

        if (c == -1 || (same_line && c == '\n'))
                return NULL;
        s->last_line = line;

        if (c == '(' ||
            c == ')' ||
            c == '+' ||
            c == '*' ||
            c == '%' ||
            c == '?' ||
            c == '^' ||
            c == '@' ||
            c == '$' ||
            c == ',' ||
            c == '.' ||
            c == ';' ||
            c == '[' ||
            c == ']' ||
            c == '{' ||
            c == '}') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                tok->type = (enum isl_token_type)c;
                return tok;
        }
        if (c == '-') {
                int c;
                if ((c = isl_stream_getc(s)) == '>') {
                        tok = isl_token_new(s->ctx, line, col, old_line != line);
                        if (!tok)
                                return NULL;
                        tok->u.s = strdup("->");
                        tok->type = ISL_TOKEN_TO;
                        return tok;
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                if (!isdigit(c)) {
                        tok = isl_token_new(s->ctx, line, col, old_line != line);
                        if (!tok)
                                return NULL;
                        tok->type = (enum isl_token_type) '-';
                        return tok;
                }
        }
        if (c == '-' || isdigit(c)) {
                int minus = c == '-';
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                tok->type = ISL_TOKEN_VALUE;
                isl_int_init(tok->u.v);
                if (isl_stream_push_char(s, c))
                        goto error;
                while ((c = isl_stream_getc(s)) != -1 && isdigit(c))
                        if (isl_stream_push_char(s, c))
                                goto error;
                if (c != -1)
                        isl_stream_ungetc(s, c);
                isl_stream_push_char(s, '\0');
                isl_int_read(tok->u.v, s->buffer);
                if (minus && isl_int_is_zero(tok->u.v)) {
                        tok->col++;
                        tok->on_new_line = 0;
                        isl_stream_push_token(s, tok);
                        tok = isl_token_new(s->ctx, line, col, old_line != line);
                        if (!tok)
                                return NULL;
                        tok->type = (enum isl_token_type) '-';
                }
                return tok;
        }
        if (isalpha(c) || c == '_') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                isl_stream_push_char(s, c);
                while ((c = isl_stream_getc(s)) != -1 &&
                                (isalnum(c) || c == '_'))
                        isl_stream_push_char(s, c);
                if (c != -1)
                        isl_stream_ungetc(s, c);
                while ((c = isl_stream_getc(s)) != -1 && c == '\'')
                        isl_stream_push_char(s, c);
                if (c != -1)
                        isl_stream_ungetc(s, c);
                isl_stream_push_char(s, '\0');
                tok->type = check_keywords(s);
                if (tok->type != ISL_TOKEN_IDENT)
                        tok->is_keyword = 1;
                tok->u.s = strdup(s->buffer);
                if (!tok->u.s)
                        goto error;
                return tok;
        }
        if (c == '"') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                tok->type = ISL_TOKEN_STRING;
                tok->u.s = NULL;
                while ((c = isl_stream_getc(s)) != -1 && c != '"' && c != '\n')
                        isl_stream_push_char(s, c);
                if (c != '"') {
                        isl_stream_error(s, NULL, "unterminated string");
                        goto error;
                }
                isl_stream_push_char(s, '\0');
                tok->u.s = strdup(s->buffer);
                return tok;
        }
        if (c == '=') {
                int c;
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) == '=') {
                        tok->u.s = strdup("==");
                        tok->type = ISL_TOKEN_EQ_EQ;
                        return tok;
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                tok->type = (enum isl_token_type) '=';
                return tok;
        }
        if (c == ':') {
                int c;
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) == '=') {
                        tok->u.s = strdup(":=");
                        tok->type = ISL_TOKEN_DEF;
                        return tok;
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                tok->type = (enum isl_token_type) ':';
                return tok;
        }
        if (c == '>') {
                int c;
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) == '=') {
                        tok->u.s = strdup(">=");
                        tok->type = ISL_TOKEN_GE;
                        return tok;
                } else if (c == '>') {
                        if ((c = isl_stream_getc(s)) == '=') {
                                tok->u.s = strdup(">>=");
                                tok->type = ISL_TOKEN_LEX_GE;
                                return tok;
                        }
                        tok->u.s = strdup(">>");
                        tok->type = ISL_TOKEN_LEX_GT;
                } else {
                        tok->u.s = strdup(">");
                        tok->type = ISL_TOKEN_GT;
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                return tok;
        }
        if (c == '<') {
                int c;
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) == '=') {
                        tok->u.s = strdup("<=");
                        tok->type = ISL_TOKEN_LE;
                        return tok;
                } else if (c == '<') {
                        if ((c = isl_stream_getc(s)) == '=') {
                                tok->u.s = strdup("<<=");
                                tok->type = ISL_TOKEN_LEX_LE;
                                return tok;
                        }
                        tok->u.s = strdup("<<");
                        tok->type = ISL_TOKEN_LEX_LT;
                } else {
                        tok->u.s = strdup("<");
                        tok->type = ISL_TOKEN_LT;
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                return tok;
        }
        if (c == '&') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                tok->type = ISL_TOKEN_AND;
                if ((c = isl_stream_getc(s)) != '&' && c != -1) {
                        tok->u.s = strdup("&");
                        isl_stream_ungetc(s, c);
                } else
                        tok->u.s = strdup("&&");
                return tok;
        }
        if (c == '|') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                tok->type = ISL_TOKEN_OR;
                if ((c = isl_stream_getc(s)) != '|' && c != -1) {
                        tok->u.s = strdup("|");
                        isl_stream_ungetc(s, c);
                } else
                        tok->u.s = strdup("||");
                return tok;
        }
        if (c == '/') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) != '\\' && c != -1) {
                        tok->type = (enum isl_token_type) '/';
                        isl_stream_ungetc(s, c);
                } else {
                        tok->u.s = strdup("/\\");
                        tok->type = ISL_TOKEN_AND;
                }
                return tok;
        }
        if (c == '\\') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) != '/' && c != -1) {
                        tok->type = (enum isl_token_type) '\\';
                        isl_stream_ungetc(s, c);
                } else {
                        tok->u.s = strdup("\\/");
                        tok->type = ISL_TOKEN_OR;
                }
                return tok;
        }
        if (c == '!') {
                tok = isl_token_new(s->ctx, line, col, old_line != line);
                if (!tok)
                        return NULL;
                if ((c = isl_stream_getc(s)) == '=') {
                        tok->u.s = strdup("!=");
                        tok->type = ISL_TOKEN_NE;
                        return tok;
                } else {
                        tok->type = ISL_TOKEN_NOT;
                        tok->u.s = strdup("!");
                }
                if (c != -1)
                        isl_stream_ungetc(s, c);
                return tok;
        }

        tok = isl_token_new(s->ctx, line, col, old_line != line);
        if (!tok)
                return NULL;
        tok->type = ISL_TOKEN_UNKNOWN;
        return tok;
error:
        isl_token_free(tok);
        return NULL;
}

struct isl_token *isl_stream_next_token(__isl_keep isl_stream *s)
{
        return next_token(s, 0);
}

struct isl_token *isl_stream_next_token_on_same_line(__isl_keep isl_stream *s)
{
        return next_token(s, 1);
}

int isl_stream_eat_if_available(__isl_keep isl_stream *s, int type)
{
        struct isl_token *tok;

        tok = isl_stream_next_token(s);
        if (!tok)
                return 0;
        if (tok->type == type) {
                isl_token_free(tok);
                return 1;
        }
        isl_stream_push_token(s, tok);
        return 0;
}

int isl_stream_next_token_is(__isl_keep isl_stream *s, int type)
{
        struct isl_token *tok;
        int r;

        tok = isl_stream_next_token(s);
        if (!tok)
                return 0;
        r = tok->type == type;
        isl_stream_push_token(s, tok);
        return r;
}

char *isl_stream_read_ident_if_available(__isl_keep isl_stream *s)
{
        struct isl_token *tok;

        tok = isl_stream_next_token(s);
        if (!tok)
                return NULL;
        if (tok->type == ISL_TOKEN_IDENT) {
                char *ident = strdup(tok->u.s);
                isl_token_free(tok);
                return ident;
        }
        isl_stream_push_token(s, tok);
        return NULL;
}

int isl_stream_eat(__isl_keep isl_stream *s, int type)
{
        struct isl_token *tok;

        tok = isl_stream_next_token(s);
        if (!tok) {
                if (s->eof)
                        isl_stream_error(s, NULL, "unexpected EOF");
                return -1;
        }
        if (tok->type == type) {
                isl_token_free(tok);
                return 0;
        }
        isl_stream_error(s, tok, "expecting other token");
        isl_stream_push_token(s, tok);
        return -1;
}

int isl_stream_is_empty(__isl_keep isl_stream *s)
{
        struct isl_token *tok;

        tok = isl_stream_next_token(s);

        if (!tok)
                return 1;

        isl_stream_push_token(s, tok);
        return 0;
}

static isl_stat free_keyword(void **p, void *user)
{
        struct isl_keyword *keyword = *p;

        free(keyword->name);
        free(keyword);

        return isl_stat_ok;
}

void isl_stream_flush_tokens(__isl_keep isl_stream *s)
{
        int i;

        if (!s)
                return;
        for (i = 0; i < s->n_token; ++i)
                isl_token_free(s->tokens[i]);
        s->n_token = 0;
}

isl_ctx *isl_stream_get_ctx(__isl_keep isl_stream *s)
{
        return s ? s->ctx : NULL;
}

void isl_stream_free(__isl_take isl_stream *s)
{
        if (!s)
                return;
        free(s->buffer);
        if (s->n_token != 0) {
                struct isl_token *tok = isl_stream_next_token(s);
                isl_stream_error(s, tok, "unexpected token");
                isl_token_free(tok);
        }
        if (s->keywords) {
                isl_hash_table_foreach(s->ctx, s->keywords, &free_keyword, NULL);
                isl_hash_table_free(s->ctx, s->keywords);
        }
        free(s->yaml_state);
        free(s->yaml_indent);
        isl_ctx_deref(s->ctx);
        free(s);
}

/* Push "state" onto the stack of currently active YAML elements.
 * The caller is responsible for setting the corresponding indentation.
 * Return 0 on success and -1 on failure.
 */
static int push_state(__isl_keep isl_stream *s, enum isl_yaml_state state)
{
        if (s->yaml_size < s->yaml_depth + 1) {
                int *indent;
                enum isl_yaml_state *state;

                state = isl_realloc_array(s->ctx, s->yaml_state,
                                        enum isl_yaml_state, s->yaml_depth + 1);
                if (!state)
                        return -1;
                s->yaml_state = state;

                indent = isl_realloc_array(s->ctx, s->yaml_indent,
                                        int, s->yaml_depth + 1);
                if (!indent)
                        return -1;
                s->yaml_indent = indent;

                s->yaml_size = s->yaml_depth + 1;
        }

        s->yaml_state[s->yaml_depth] = state;
        s->yaml_depth++;

        return 0;
}

/* Remove the innermost active YAML element from the stack.
 * Return 0 on success and -1 on failure.
 */
static int pop_state(__isl_keep isl_stream *s)
{
        if (!s)
                return -1;
        if (s->yaml_depth < 1)
                isl_die(isl_stream_get_ctx(s), isl_error_invalid,
                        "not in YAML construct", return -1);

        s->yaml_depth--;

        return 0;
}

/* Set the state of the innermost active YAML element to "state".
 * Return 0 on success and -1 on failure.
 */
static int update_state(__isl_keep isl_stream *s, enum isl_yaml_state state)
{
        if (!s)
                return -1;
        if (s->yaml_depth < 1)
                isl_die(isl_stream_get_ctx(s), isl_error_invalid,
                        "not in YAML construct", return -1);

        s->yaml_state[s->yaml_depth - 1] = state;

        return 0;
}

/* Return the state of the innermost active YAML element.
 * Return isl_yaml_none if we are not inside any YAML element.
 */
static enum isl_yaml_state current_state(__isl_keep isl_stream *s)
{
        if (!s)
                return isl_yaml_none;
        if (s->yaml_depth < 1)
                return isl_yaml_none;
        return s->yaml_state[s->yaml_depth - 1];
}

/* Set the indentation of the innermost active YAML element to "indent".
 * If "indent" is equal to ISL_YAML_INDENT_FLOW, then this means
 * that the current elemient is in flow format.
 */
static int set_yaml_indent(__isl_keep isl_stream *s, int indent)
{
        if (s->yaml_depth < 1)
                isl_die(s->ctx, isl_error_internal,
                        "not in YAML element", return -1);

        s->yaml_indent[s->yaml_depth - 1] = indent;

        return 0;
}

/* Return the indentation of the innermost active YAML element
 * of -1 on error.
 */
static int get_yaml_indent(__isl_keep isl_stream *s)
{
        if (s->yaml_depth < 1)
                isl_die(s->ctx, isl_error_internal,
                        "not in YAML element", return -1);

        return s->yaml_indent[s->yaml_depth - 1];
}

/* Move to the next state at the innermost level.
 * Return 1 if successful.
 * Return 0 if we are at the end of the innermost level.
 * Return -1 on error.
 *
 * If we are in state isl_yaml_mapping_key_start, then we have just
 * started a mapping and we are expecting a key.  If the mapping started
 * with a '{', then we check if the next token is a '}'.  If so,
 * then the mapping is empty and there is no next state at this level.
 * Otherwise, we assume that there is at least one key (the one from
 * which we derived the indentation in isl_stream_yaml_read_start_mapping.
 *
 * If we are in state isl_yaml_mapping_key, then the we expect a colon
 * followed by a value, so there is always a next state unless
 * some error occurs.
 *
 * If we are in state isl_yaml_mapping_val, then there may or may
 * not be a subsequent key in the same mapping.
 * In flow format, the next key is preceded by a comma.
 * In block format, the next key has the same indentation as the first key.
 * If the first token has a smaller indentation, then we have reached
 * the end of the current mapping.
 *
 * If we are in state isl_yaml_sequence_start, then we have just
 * started a sequence.  If the sequence started with a '[',
 * then we check if the next token is a ']'.  If so, then the sequence
 * is empty and there is no next state at this level.
 * Otherwise, we assume that there is at least one element in the sequence
 * (the one from which we derived the indentation in
 * isl_stream_yaml_read_start_sequence.
 *
 * If we are in state isl_yaml_sequence, then there may or may
 * not be a subsequent element in the same sequence.
 * In flow format, the next element is preceded by a comma.
 * In block format, the next element is introduced by a dash with
 * the same indentation as that of the first element.
 * If the first token is not a dash or if it has a smaller indentation,
 * then we have reached the end of the current sequence.
 */
int isl_stream_yaml_next(__isl_keep isl_stream *s)
{
        struct isl_token *tok;
        enum isl_yaml_state state;
        int indent;

        state = current_state(s);
        if (state == isl_yaml_none)
                isl_die(s->ctx, isl_error_invalid,
                        "not in YAML element", return -1);
        switch (state) {
        case isl_yaml_mapping_key_start:
                if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW &&
                    isl_stream_next_token_is(s, '}'))
                        return 0;
                if (update_state(s, isl_yaml_mapping_key) < 0)
                        return -1;
                return 1;
        case isl_yaml_mapping_key:
                tok = isl_stream_next_token(s);
                if (!tok) {
                        if (s->eof)
                                isl_stream_error(s, NULL, "unexpected EOF");
                        return -1;
                }
                if (tok->type == ':') {
                        isl_token_free(tok);
                        if (update_state(s, isl_yaml_mapping_val) < 0)
                                return -1;
                        return 1;
                }
                isl_stream_error(s, tok, "expecting ':'");
                isl_stream_push_token(s, tok);
                return -1;
        case isl_yaml_mapping_val:
                if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW) {
                        if (!isl_stream_eat_if_available(s, ','))
                                return 0;
                        if (update_state(s, isl_yaml_mapping_key) < 0)
                                return -1;
                        return 1;
                }
                tok = isl_stream_next_token(s);
                if (!tok)
                        return 0;
                indent = tok->col - 1;
                isl_stream_push_token(s, tok);
                if (indent < get_yaml_indent(s))
                        return 0;
                if (update_state(s, isl_yaml_mapping_key) < 0)
                        return -1;
                return 1;
        case isl_yaml_sequence_start:
                if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW) {
                        if (isl_stream_next_token_is(s, ']'))
                                return 0;
                        if (update_state(s, isl_yaml_sequence) < 0)
                                return -1;
                        return 1;
                }
                tok = isl_stream_next_token(s);
                if (!tok) {
                        if (s->eof)
                                isl_stream_error(s, NULL, "unexpected EOF");
                        return -1;
                }
                if (tok->type == '-') {
                        isl_token_free(tok);
                        if (update_state(s, isl_yaml_sequence) < 0)
                                return -1;
                        return 1;
                }
                isl_stream_error(s, tok, "expecting '-'");
                isl_stream_push_token(s, tok);
                return 0;
        case isl_yaml_sequence:
                if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW)
                        return isl_stream_eat_if_available(s, ',');
                tok = isl_stream_next_token(s);
                if (!tok)
                        return 0;
                indent = tok->col - 1;
                if (indent < get_yaml_indent(s) || tok->type != '-') {
                        isl_stream_push_token(s, tok);
                        return 0;
                }
                isl_token_free(tok);
                return 1;
        default:
                isl_die(s->ctx, isl_error_internal,
                        "unexpected state", return 0);
        }
}

/* Start reading a YAML mapping.
 * Return 0 on success and -1 on error.
 *
 * If the first token on the stream is a '{' then we remove this token
 * from the stream and keep track of the fact that the mapping
 * is given in flow format.
 * Otherwise, we assume the first token is the first key of the mapping and
 * keep track of its indentation, but keep the token on the stream.
 * In both cases, the next token we expect is the first key of the mapping.
 */
int isl_stream_yaml_read_start_mapping(__isl_keep isl_stream *s)
{
        struct isl_token *tok;
        int indent;

        if (push_state(s, isl_yaml_mapping_key_start) < 0)
                return -1;

        tok = isl_stream_next_token(s);
        if (!tok) {
                if (s->eof)
                        isl_stream_error(s, NULL, "unexpected EOF");
                return -1;
        }
        if (isl_token_get_type(tok) == '{') {
                isl_token_free(tok);
                return set_yaml_indent(s, ISL_YAML_INDENT_FLOW);
        }
        indent = tok->col - 1;
        isl_stream_push_token(s, tok);

        return set_yaml_indent(s, indent);
}

/* Finish reading a YAML mapping.
 * Return 0 on success and -1 on error.
 *
 * If the mapping started with a '{', then we expect a '}' to close
 * the mapping.
 * Otherwise, we double-check that the next token (if any)
 * has a smaller indentation than that of the current mapping.
 */
int isl_stream_yaml_read_end_mapping(__isl_keep isl_stream *s)
{
        struct isl_token *tok;
        int indent;

        if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW) {
                if (isl_stream_eat(s, '}') < 0)
                        return -1;
                return pop_state(s);
        }

        tok = isl_stream_next_token(s);
        if (!tok)
                return pop_state(s);

        indent = tok->col - 1;
        isl_stream_push_token(s, tok);

        if (indent >= get_yaml_indent(s))
                isl_die(isl_stream_get_ctx(s), isl_error_invalid,
                        "mapping not finished", return -1);

        return pop_state(s);
}

/* Start reading a YAML sequence.
 * Return 0 on success and -1 on error.
 *
 * If the first token on the stream is a '[' then we remove this token
 * from the stream and keep track of the fact that the sequence
 * is given in flow format.
 * Otherwise, we assume the first token is the dash that introduces
 * the first element of the sequence and keep track of its indentation,
 * but keep the token on the stream.
 * In both cases, the next token we expect is the first element
 * of the sequence.
 */
int isl_stream_yaml_read_start_sequence(__isl_keep isl_stream *s)
{
        struct isl_token *tok;
        int indent;

        if (push_state(s, isl_yaml_sequence_start) < 0)
                return -1;

        tok = isl_stream_next_token(s);
        if (!tok) {
                if (s->eof)
                        isl_stream_error(s, NULL, "unexpected EOF");
                return -1;
        }
        if (isl_token_get_type(tok) == '[') {
                isl_token_free(tok);
                return set_yaml_indent(s, ISL_YAML_INDENT_FLOW);
        }
        indent = tok->col - 1;
        isl_stream_push_token(s, tok);

        return set_yaml_indent(s, indent);
}

/* Finish reading a YAML sequence.
 * Return 0 on success and -1 on error.
 *
 * If the sequence started with a '[', then we expect a ']' to close
 * the sequence.
 * Otherwise, we double-check that the next token (if any)
 * is not a dash or that it has a smaller indentation than
 * that of the current sequence.
 */
int isl_stream_yaml_read_end_sequence(__isl_keep isl_stream *s)
{
        struct isl_token *tok;
        int indent;
        int dash;

        if (get_yaml_indent(s) == ISL_YAML_INDENT_FLOW) {
                if (isl_stream_eat(s, ']') < 0)
                        return -1;
                return pop_state(s);
        }

        tok = isl_stream_next_token(s);
        if (!tok)
                return pop_state(s);

        indent = tok->col - 1;
        dash = tok->type == '-';
        isl_stream_push_token(s, tok);

        if (indent >= get_yaml_indent(s) && dash)
                isl_die(isl_stream_get_ctx(s), isl_error_invalid,
                        "sequence not finished", return -1);

        return pop_state(s);
}