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#include "parse.h"
#include <stdbool.h>
#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include "log.h"
enum ParsePhase {
PHASE_COUNT,
PHASE_BUILD,
};
struct ParseCtx {
char * const str;
char *cursor;
struct Tree *tree;
size_t tree_cursor;
size_t *chunks;
enum ParsePhase phase;
};
static uint64_t max(uint64_t a, uint64_t b) {
return a > b ? a : b;
}
static bool alnum(struct ParseCtx *ctx) {
return isalnum(ctx->cursor[0]);
}
static int read_STag(struct ParseCtx *ctx, bool *self_close, size_t nodeId) {
// Record start position of the tag
if (ctx->phase == PHASE_BUILD) {
ctx->chunks[nodeId] = ctx->cursor - ctx->str;
}
if(*ctx->cursor != '<') return 1;
ctx->cursor++;
while(isalnum(*ctx->cursor) || *ctx->cursor == ' ' || *ctx->cursor == '"' || *ctx->cursor == '=') ctx->cursor++;
// Check for self-closing tag
if(*ctx->cursor == '/') {
*self_close = true;
ctx->cursor++;
}
if(*ctx->cursor != '>') return 1;
ctx->cursor++;
return 0;
}
static int read_Element(struct ParseCtx *ctx, size_t nodeId);
static int read_Content(struct ParseCtx *ctx, size_t nodeId) {
int err;
uint64_t children = 0;
while(true) {
if(ctx->cursor[0] == '<' && ctx->cursor[1] != '/') {
size_t childId = ctx->tree_cursor++;
err = read_Element(ctx, childId);
if(err != 0) return err;
if(ctx->phase == PHASE_BUILD)
*imat_nid(ctx->tree->adj, children, nodeId) = childId+1;
children++;
} else if(alnum(ctx)) {
ctx->cursor++;
} else {
break;
}
}
if(ctx->phase == PHASE_COUNT)
ctx->tree->adj.stride = max(ctx->tree->adj.stride, children);
if(ctx->phase == PHASE_BUILD) {
for(size_t i = children; i < ctx->tree->adj.stride; i++) {
*imat_nid(ctx->tree->adj, i, nodeId) = 0;
}
}
return 0;
}
static int read_ETag(struct ParseCtx *ctx) {
if(*ctx->cursor != '<') return 1;
ctx->cursor++;
if(*ctx->cursor != '/') return 1;
ctx->cursor++;
while(isalnum(*ctx->cursor)) ctx->cursor++;
if(*ctx->cursor != '>') return 1;
ctx->cursor++;
return 0;
}
static int read_Element(struct ParseCtx *ctx, size_t nodeId) {
int err;
bool self_close = false;
err = read_STag(ctx, &self_close, nodeId);
if(err != 0) return err;
if(!self_close) {
err = read_Content(ctx, nodeId);
if(err != 0) return err;
err = read_ETag(ctx);
if(err != 0) return err;
} else if(ctx->phase == PHASE_BUILD) {
for(size_t i = 0; i < ctx->tree->adj.stride; i++)
*imat_nid(ctx->tree->adj, i, nodeId) = 0;
}
if(ctx->phase == PHASE_COUNT) ctx->tree->len++;
return 0;
}
// This follows a 2 phase approach. First we size out the tree to figure out how
// much data we are going to store. Then we allocate the space based on that
// count pass before then doing a second pass in the BUILD phase which fill in
// those data structures.
int parse_string(char *str, struct Tree *tree, size_t **chunks) {
assert(chunks != NULL); // Chunks parameter is required
tree->adj.stride = 1;
tree->len = 0;
struct ParseCtx ctx = {
.str = str,
.cursor = str,
.tree = tree,
.tree_cursor = 1,
.phase = PHASE_COUNT,
};
int err;
err = read_Element(&ctx, 0);
if(err != 0) {
log("Parse error at %ld", ctx.cursor - ctx.str);
return err;
}
tree->adj.data = malloc(tree->len * tree->adj.stride * sizeof(*tree->adj.data));
// Allocate memory for chunks
*chunks = malloc(tree->len * sizeof(size_t));
if (*chunks == NULL) {
free(tree->adj.data);
return 1;
}
// Reset the context for the next phase
ctx.phase = PHASE_BUILD;
ctx.cursor = str;
ctx.tree_cursor = 1;
ctx.chunks = *chunks;
err = read_Element(&ctx, 0);
// The second phase we assume the tree is valid since it passed the first phase
assert(err == 0);
return 0;
}
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