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#include "ast.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void free_ast_command(struct AST *ast) {
free_ast(ast->children);
free_ast(ast->pipe_rhs);
}
void free_ast(struct AST *ast) {
for (; ast;) {
if (AST_COMMAND == ast->type)
free_ast_command(ast);
struct AST *old = ast;
ast = ast->next;
free(old);
}
}
struct AST *allocate_ast(void) {
struct AST *r = malloc(sizeof(struct AST));
memset(r, 0, sizeof(struct AST));
return r;
}
int parse_command(struct TOKEN **token_ptr, struct AST *cur) {
struct TOKEN *token = *token_ptr;
if (TOKEN_CHARS != token->type)
return 0;
cur->type = AST_COMMAND;
cur->val.type = AST_VALUE_STRING;
cur->val.string = token->string_rep;
// Parse the arguments
if (token->next && TOKEN_CHARS == token->next->type) {
token = token->next;
cur->children = allocate_ast();
struct AST *child = cur->children;
for (;;) {
child->type = AST_EXPRESSION;
child->val.type = AST_VALUE_STRING;
child->val.string = token->string_rep;
if (!token->next)
break;
if (TOKEN_CHARS != token->next->type)
break;
token = token->next;
child->next = allocate_ast();
child = child->next;
}
}
token = token->next;
// Parse the stream modifier "prog > file.txt"
if (token &&
(TOKEN_STREAM == token->type || TOKEN_STREAM_APPEND == token->type)) {
cur->file_out_append = (TOKEN_STREAM_APPEND == token->type);
// TODO: Allow it to be modified
cur->file_out_fd_to_use = STDOUT_FILENO;
token = token->next;
cur->file_out = token->string_rep;
token = token->next;
}
// Parse '&'
if (token && TOKEN_BACKGROUND == token->type) {
cur->should_background = 1;
token = token->next;
}
// Parse pipe '|'
if (token && TOKEN_PIPE == token->type) {
cur->pipe_rhs = allocate_ast();
token = token->next;
if (!parse_command(&token, cur->pipe_rhs)) {
fprintf(stderr, "Expected command after |.");
exit(1);
}
}
if (token && TOKEN_NEWLINE == token->type) {
token = token->next;
}
*token_ptr = token;
return 1;
}
struct AST *generate_ast(struct TOKEN *token) {
struct AST *head = NULL;
struct AST *prev = NULL;
for (; token;) {
struct AST *cur = allocate_ast();
if (prev)
prev->next = cur;
if (parse_command(&token, cur)) {
} else if (TOKEN_AND == token->type) {
cur->type = AST_CONDITIONAL_AND;
token = token->next;
} else if (TOKEN_NOT == token->type) {
cur->type = AST_CONDITIONAL_NOT;
token = token->next;
} else {
token = token->next;
}
if (!head)
head = cur;
prev = cur;
}
return head;
}
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