const correct crossref

Author: Joshua Goller

ch-6/crossref/include/crossref.h

@@ -11,15 +11,15 @@ typedef struct word_node {
 } word_node;
 
 // io.c
-int getword(char* word);
+int getword(char* const word);
 
 // node.c
-int add_line(word_node* node, size_t line_no);
-void display_lines(word_node* node);
+word_node* create_node(const char* const word);
+int add_line(word_node* const node, const size_t line_no);
+void display_lines(const word_node* const node);
 
 // tree.c
-word_node* create_node(char* word);
-word_node* tree_insert(char* word, word_node* node);
-word_node* tree_search(char* word, word_node* node);
-void tree_walk(word_node* head);
+word_node* tree_insert(const char* const word, word_node* const node);
+word_node* tree_search(const char* const word, const word_node* const node);
+void tree_walk(const word_node* const head);
 void tree_cleanup(word_node* head);

ch-6/crossref/src/io.c

@@ -15,7 +15,7 @@ static int is_noise_word( char*  word, word_node* noise_words) {
 
 // getword(): get the next word from input. Returns the last
 // char read, or EOF
-int getword(char* word) {
+int getword(char* const word) {
   int i = 0;
   int c = 0;
   c = getchar();

ch-6/crossref/src/node.c

@@ -6,7 +6,7 @@
 #include "crossref.h"
 
 // create_node(): allocate a new node
-word_node* create_node(char* word) {
+word_node* create_node(const char* const word) {
   if (word == NULL) {
     printf("create_node() | cannot create node for null string.\n");
     return NULL;
@@ -47,7 +47,7 @@ word_node* create_node(char* word) {
 }
 
 // add_line(): add a line number to a node's list of lines
-int add_line(word_node* node, size_t line_no) {
+int add_line(word_node* const node, const size_t line_no) {
   if (node == NULL) {
     return -1;
   }
@@ -76,7 +76,7 @@ int add_line(word_node* node, size_t line_no) {
 }
 
 // display_line(): display all lines in line buffer
-void display_lines(word_node* node) {
+void display_lines(const word_node* const node) {
   printf("%s (n: %lu, max: %lu): ", node->word, node->lines_n, node->lines_max);
   for (size_t i = 0; i < node->lines_n; i++) {
     printf("%lu ", node->lines[i]);

ch-6/crossref/src/tree.c

@@ -2,10 +2,12 @@
 #include <stdlib.h>
 #include <string.h>
 
+#pragma clang diagnostic ignored "-Wcast-qual"
+
 #include "crossref.h"
 
 // tree_insert(): insert word in tree
-word_node* tree_insert(char* word, word_node* node) {
+word_node* tree_insert(const char* const word, word_node* const node) {
   if (node == NULL) {
     return NULL;
   }
@@ -36,15 +38,15 @@ word_node* tree_insert(char* word, word_node* node) {
 }
 
 // tree_search(): return node in tree storing word, or NULL
-word_node* tree_search(char* word, word_node* node) {
+word_node* tree_search(const char* const word, const word_node* const node) {
   if (node == NULL) {
     return NULL;
   }
 
   // walk tree based on comparison to word
   int result = strcmp(node->word, word);
   if (result == 0) {
-    return node;
+    return (word_node*)node;
   } else if (result < 0) {
     return tree_search(word, node->left);
   } else {
@@ -53,7 +55,7 @@ word_node* tree_search(char* word, word_node* node) {
 }
 
 // tree_walk(): post-order walk the tree, printing strings and line buffers
-void tree_walk(word_node* head) {
+void tree_walk(const word_node* const head) {
   if (head == NULL) {
     return;
   }