mds-kbdc: variables

Signed-off-by: Mattias Andrée <maandree@operamail.com>

9 files changed, 392 insertions, 43 deletions

diff --git a/src/mds-kbdc/builtin-functions.c b/src/mds-kbdc/builtin-functions.c
index cfac8ac..0cb7aa6 100644
--- a/src/mds-kbdc/builtin-functions.c
+++ b/src/mds-kbdc/builtin-functions.c
@@ -17,6 +17,8 @@
  */
 #include "builtin-functions.h"
 
+#include "variables.h"
+
 #include <stdlib.h>
 #include <string.h>
 
@@ -258,8 +260,45 @@ static char32_t* builtin_function_less_2(const char32_t** restrict args)
 }
 
 
-/* static char32_t* builtin_function_set_3(const char32_t** restrict args);  (variable index value) */
-/* static char32_t* builtin_function_get_2(const char32_t** restrict args);  (variable index) */
+/**
+ * Definition of the built-in function get/2
+ * 
+ * @param   args  The arguments passed to the function
+ * @return        The return value of the function, `NULL` on error
+ */
+static char32_t* builtin_function_get_2(const char32_t** restrict args)
+{
+  const char32_t* restrict a = *args++;
+  const char32_t* restrict b = *args++;
+  size_t n = (size_t)*b;
+  mds_kbdc_tree_t* value = variables_get((size_t)*a);
+  while (n--)
+    value = value->next;
+  return string_dup(value->compiled_string.string);
+}
+
+
+/**
+ * Definition of the built-in function set/3
+ * 
+ * @param   args  The arguments passed to the function
+ * @return        The return value of the function, `NULL` on error
+ */
+static char32_t* builtin_function_set_3(const char32_t** restrict args)
+{
+  const char32_t* restrict a = *args++;
+  const char32_t* restrict b = *args++;
+  const char32_t* restrict c = *args++;
+  size_t n = (size_t)*b;
+  mds_kbdc_tree_t* value = variables_get((size_t)*a);
+  while (n--)
+    value = value->next;
+  free(value->compiled_string.string);
+  value->compiled_string.string = string_dup(c);
+  if (value->compiled_string.string == NULL)
+    return NULL;
+  return string_dup(c);
+}
 
 
 #undef define_1
@@ -298,6 +337,10 @@ int builtin_function_defined(const char* restrict name, size_t arg_count)
 /**
  * Invoke a builtin function
  * 
+ * The function will abort if an non-builtin function is addressed
+ * 
+ * Before invoking set/3 or get/2, please check the arguments
+ * 
  * @param   name       The name of the function
  * @param   arg_count  The number of arguments to pass to the function
  * @param   args       The arguments to pass
@@ -307,14 +350,14 @@ char32_t* builtin_function_invoke(const char* restrict name, size_t arg_count, c
 {
   if (arg_count == 3)
     if (!strcmp(name, "set"))
-      return NULL; /* TODO builtin_function_set_3(args) */
+      return builtin_function_set_3(args);
   
   if (arg_count == 1)
     if (!strcmp(name, "not"))
       return builtin_function_not_1(args);
   
   if (arg_count != 2)
-    return NULL;
+    abort();
   
   if (!strcmp(name, "add"))      return builtin_function_add_2(args);
   if (!strcmp(name, "sub"))      return builtin_function_sub_2(args);
@@ -329,8 +372,8 @@ char32_t* builtin_function_invoke(const char* restrict name, size_t arg_count, c
   if (!strcmp(name, "equals"))   return builtin_function_equals_2(args);
   if (!strcmp(name, "greater"))  return builtin_function_greater_2(args);
   if (!strcmp(name, "less"))     return builtin_function_less_2(args);
-  if (!strcmp(name, "get"))      return NULL; /* TODO builtin_function_get_2(args) */
+  if (!strcmp(name, "get"))      return builtin_function_get_2(args);
   
-  return NULL;
+  abort();
 }
 
diff --git a/src/mds-kbdc/builtin-functions.h b/src/mds-kbdc/builtin-functions.h
index ebe3935..5c78f0e 100644
--- a/src/mds-kbdc/builtin-functions.h
+++ b/src/mds-kbdc/builtin-functions.h
@@ -38,6 +38,10 @@ int builtin_function_defined(const char* restrict name, size_t arg_count) __attr
 /**
  * Invoke a builtin function
  * 
+ * The function will abort if an non-builtin function is addressed
+ * 
+ * Before invoking set/3 or get/2, please check the arguments
+ * 
  * @param   name       The name of the function
  * @param   arg_count  The number of arguments to pass to the function
  * @param   args       The arguments to pass
diff --git a/src/mds-kbdc/compile-layout.c b/src/mds-kbdc/compile-layout.c
index cdf8df6..3239482 100644
--- a/src/mds-kbdc/compile-layout.c
+++ b/src/mds-kbdc/compile-layout.c
@@ -21,6 +21,7 @@
 #include "include-stack.h"
 #include "builtin-functions.h"
 #include "string.h"
+#include "variables.h"
 
 #include <stdlib.h>
 #include <errno.h>
@@ -144,27 +145,53 @@ static size_t parse_variable(mds_kbdc_tree_t* restrict tree, const char* restric
   return 0; /* TODO */
 }
 
+
+/**
+ * Assign a value to a variable, and define or shadow it in the process
+ * 
+ * @param   variable                  The variable index
+ * @param   string                    The variable's new value, must be `NULL` iff `value != NULL`
+ * @param   value                     The variable's new value, must be `NULL` iff `string != NULL`
+ * @param   statement                 The statement where the variable is assigned, may be `NULL`
+ * @param   lineoff                   The offset of the line for where the string selecting the variable begins
+ * @param   possibile_shadow_attempt  Whether `statement` is of a type that does not shadow variables,
+ *                                    but could easily be mistaked for one that does
+ * @return                            Zero on success, -1 on error
+ */
 static int let(size_t variable, const char32_t* restrict string, const mds_kbdc_tree_t* restrict value,
 	       mds_kbdc_tree_t* restrict statement, size_t lineoff, int possibile_shadow_attempt)
 {
-  (void) variable;
-  (void) string;
-  (void) value;
-  (void) statement;
-  (void) lineoff;
-  (void) possibile_shadow_attempt;
-  return 0; /* TODO */
-}
-
-static int push_stack(void)
-{
-  return 0; /* TODO */
+  mds_kbdc_tree_t* tree = NULL;
+  int saved_errno;
+  
+  /* Warn if this is a possible shadow attempt. */
+  if (possibile_shadow_attempt && variables_let_will_override(variable) &&
+      statement && (statement->processed != PROCESS_LEVEL))
+    {
+      statement->processed = PROCESS_LEVEL;
+      NEW_ERROR(statement, WARNING, "will not shadow existing definition");
+      error->start = lineoff;
+      error->end = lineoff + (size_t)snprintf(NULL, 0, "\\%zu", variable);
+    }
+  
+  /* Duplicate value. */
+  if (value)
+    fail_if ((tree = mds_kbdc_tree_dup(value), tree == NULL));
+  if (value == NULL)
+    {
+      fail_if ((tree = mds_kbdc_tree_create(C(COMPILED_STRING)), tree == NULL));
+      tree->compiled_string.string = string_dup(string);
+      fail_if (tree->compiled_string.string == NULL);
+    }
+  
+  /* Assign variable. */
+  fail_if (variables_let(variable, tree));
+  return 0;
+  FAIL_BEGIN;
+  mds_kbdc_tree_free(tree);
+  FAIL_END;
 }
 
-static int pop_stack(void)
-{
-  return 0; /* TODO */
-}
 
 static int set_macro(const mds_kbdc_tree_macro_t* restrict macro,
 		     mds_kbdc_include_stack_t* macro_include_stack)
@@ -1072,7 +1099,7 @@ static int compile_let(mds_kbdc_tree_let_t* restrict tree)
   /* Set the value of the variable. */
   fail_if (let(variable, NULL, value, NULL, 0, 0));
   
-  free(value);
+  mds_kbdc_tree_free(value);
   return 0;
   FAIL_BEGIN;
   free(value);
@@ -1339,7 +1366,7 @@ static int compile_macro_call(mds_kbdc_tree_macro_call_t* restrict tree)
   
   
   /* Push call stack and set parameters. */
-  fail_if (push_stack());
+  variables_stack_push();
   for (arg_ = arg; arg_; arg_ = arg_->next)
     fail_if (let(variable, NULL, arg_, NULL, 0, 0));
   
@@ -1355,7 +1382,7 @@ static int compile_macro_call(mds_kbdc_tree_macro_call_t* restrict tree)
   mds_kbdc_include_stack_free(our_include_stack), our_include_stack = NULL;
   
   /* Pop call stack. */
-  fail_if (pop_stack());
+  variables_stack_pop();
   
   
  done:
@@ -1446,10 +1473,14 @@ static int compile_subtree(mds_kbdc_tree_t* restrict tree)
  */
 int compile_layout(mds_kbdc_parsed_t* restrict result_)
 {
-  int r;
+  int r, saved_errno;
   mds_kbdc_include_stack_begin(result = result_);
   r = compile_subtree(result_->tree);
-  return mds_kbdc_include_stack_end(), r;
+  saved_errno = errno;
+  mds_kbdc_include_stack_end();
+  variables_terminate();
+  errno = saved_errno;
+  return r;
 }
 
 
diff --git a/src/mds-kbdc/include-stack.c b/src/mds-kbdc/include-stack.c
index dd2bc98..d86374e 100644
--- a/src/mds-kbdc/include-stack.c
+++ b/src/mds-kbdc/include-stack.c
@@ -109,18 +109,14 @@ void mds_kbdc_include_stack_begin(mds_kbdc_parsed_t* restrict result_)
 /**
  * Mark the root of the tree as no longer being visited,
  * and release clean up after the use of this module
- * 
- * This function is guaranteed not to modify `errno`
  */
 void mds_kbdc_include_stack_end(void)
 {
-  int saved_errno = errno;
   latest_save = NULL;
   result->pathname = original_pathname;
   result->source_code = original_source_code;
   free(includes), includes = NULL;
   includes_size = includes_ptr = 0;
-  errno = saved_errno;
 }
 
 
diff --git a/src/mds-kbdc/include-stack.h b/src/mds-kbdc/include-stack.h
index 49a6248..5d51a61 100644
--- a/src/mds-kbdc/include-stack.h
+++ b/src/mds-kbdc/include-stack.h
@@ -112,8 +112,6 @@ void mds_kbdc_include_stack_begin(mds_kbdc_parsed_t* restrict result);
 /**
  * Mark the root of the tree as no longer being visited,
  * and release clean up after the use of this module
- * 
- * This function is guaranteed not to modify `errno`
  */
 void mds_kbdc_include_stack_end(void);
 
diff --git a/src/mds-kbdc/tree.c b/src/mds-kbdc/tree.c
index 7493ceb..e5af0b9 100644
--- a/src/mds-kbdc/tree.c
+++ b/src/mds-kbdc/tree.c
@@ -277,9 +277,9 @@ void mds_kbdc_tree_free(mds_kbdc_tree_t* restrict this)
  * 
  * @param  LOWERCASE:identifer   The name of subtype
  */
-#define NODE(LOWERCASE)								\
-  mds_kbdc_tree_##LOWERCASE##_t* n = (mds_kbdc_tree_##LOWERCASE##_t*)node;	\
-  mds_kbdc_tree_##LOWERCASE##_t* t = (mds_kbdc_tree_##LOWERCASE##_t*)this
+#define NODE(LOWERCASE)									\
+  mds_kbdc_tree_##LOWERCASE##_t* n = (mds_kbdc_tree_##LOWERCASE##_t*)node;		\
+  const mds_kbdc_tree_##LOWERCASE##_t* t = (const mds_kbdc_tree_##LOWERCASE##_t*)this
 
 
 /**
@@ -288,7 +288,7 @@ void mds_kbdc_tree_free(mds_kbdc_tree_t* restrict this)
  * @param   this  The tree node
  * @return        A duplicate of `this`, `NULL` on error
  */
-mds_kbdc_tree_t* mds_kbdc_tree_dup(mds_kbdc_tree_t* restrict this)
+mds_kbdc_tree_t* mds_kbdc_tree_dup(const mds_kbdc_tree_t* restrict this)
 {
   mds_kbdc_tree_t* node = NULL;
   int saved_errno;
@@ -357,8 +357,8 @@ mds_kbdc_tree_t* mds_kbdc_tree_dup(mds_kbdc_tree_t* restrict this)
  * @param  NOTATION:const char*  The notation for the subtype
  */
 #define NODE(LOWERCASE, NOTATION)					\
-  mds_kbdc_tree_##LOWERCASE##_t* node;					\
-  node = (mds_kbdc_tree_##LOWERCASE##_t*)this;				\
+  const mds_kbdc_tree_##LOWERCASE##_t* node;				\
+  node = (const mds_kbdc_tree_##LOWERCASE##_t*)this;			\
   fprintf(output, "%*.s(\033[01m%s\033[00m", indent, "", NOTATION);	\
   fprintf(output, " \033[36m(@ %zu %zu-%zu)\033[00m",			\
 	  node->loc_line + 1, node->loc_start, node->loc_end)
@@ -502,7 +502,7 @@ mds_kbdc_tree_t* mds_kbdc_tree_dup(mds_kbdc_tree_t* restrict this)
  * @param  output  The output file
  * @param  indent  The indent
  */
-static void mds_kbdc_tree_print_indented(mds_kbdc_tree_t* restrict this, FILE* output, int indent)
+static void mds_kbdc_tree_print_indented(const mds_kbdc_tree_t* restrict this, FILE* output, int indent)
 {
  again:
   if (this == NULL)
@@ -605,7 +605,7 @@ static void mds_kbdc_tree_print_indented(mds_kbdc_tree_t* restrict this, FILE* o
  * @param  this    The tree node
  * @param  output  The output file
  */
-void mds_kbdc_tree_print(mds_kbdc_tree_t* restrict this, FILE* output)
+void mds_kbdc_tree_print(const mds_kbdc_tree_t* restrict this, FILE* output)
 {
   mds_kbdc_tree_print_indented(this, output, 0);
 }
diff --git a/src/mds-kbdc/tree.h b/src/mds-kbdc/tree.h
index 1c5d8d3..885839a 100644
--- a/src/mds-kbdc/tree.h
+++ b/src/mds-kbdc/tree.h
@@ -831,7 +831,7 @@ void mds_kbdc_tree_free(mds_kbdc_tree_t* restrict this);
  * @param   this  The tree node
  * @return        A duplicate of `this`, `NULL` on error
  */
-mds_kbdc_tree_t* mds_kbdc_tree_dup(mds_kbdc_tree_t* restrict this);
+mds_kbdc_tree_t* mds_kbdc_tree_dup(const mds_kbdc_tree_t* restrict this);
 
 
 /**
@@ -840,7 +840,7 @@ mds_kbdc_tree_t* mds_kbdc_tree_dup(mds_kbdc_tree_t* restrict this);
  * @param  this    The tree node
  * @param  output  The output file
  */
-void mds_kbdc_tree_print(mds_kbdc_tree_t* restrict this, FILE* output);
+void mds_kbdc_tree_print(const mds_kbdc_tree_t* restrict this, FILE* output);
 
 
 
diff --git a/src/mds-kbdc/variables.c b/src/mds-kbdc/variables.c
new file mode 100644
index 0000000..b53569a
--- /dev/null
+++ b/src/mds-kbdc/variables.c
@@ -0,0 +1,197 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "variables.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+
+/**
+ * The state of a variable
+ */
+typedef struct variable
+{
+  /**
+   * The current value of the variable
+   */
+  mds_kbdc_tree_t* value;
+  
+  /**
+   * The previous version of variable,
+   * before it was shadowed
+   */
+  struct variable* restrict previous;
+  
+  /**
+   * The original scope the current shadow
+   * of the variable was created in
+   */
+  size_t scope;
+  
+} variable_t;
+
+
+
+/**
+ * Map (by index) of defined variables
+ */
+static variable_t** restrict variables = NULL;
+
+/**
+ * The size of `variables`
+ */
+static size_t variable_count = 0;
+
+/**
+ * The current scope, the number of
+ * times the variable-stakc has been
+ * pushed without being popped
+ */
+static size_t current_scope = 0;
+
+
+
+/**
+ * Destroy the variable storage
+ */
+void variables_terminate(void)
+{
+  size_t i;
+  variable_t* old;
+  for (i = 0; i < variable_count; i++)
+    while (variables[i])
+      {
+	old = variables[i];
+	variables[i] = variables[i]->previous;
+	mds_kbdc_tree_free(old->value);
+	free(old);
+      }
+  free(variables), variables = NULL;
+  variable_count = current_scope = 0;
+}
+
+
+/**
+ * Push the variable-stack, making it
+ * possible to shadow all variables
+ */
+void variables_stack_push(void)
+{
+  current_scope++;
+}
+
+
+/**
+ * Undo the actions of `variables_stack_push`
+ * and all additions to the variable storage
+ * since it was last called (without a
+ * corresponding call to this function)
+ */
+void variables_stack_pop(void)
+{
+  size_t i;
+  variable_t* old;
+  for (i = 0; i < variable_count; i++)
+    if (variables[i] && (variables[i]->scope == current_scope))
+      {
+	old = variables[i];
+	variables[i] = variables[i]->previous;
+	mds_kbdc_tree_free(old->value);
+	free(old);
+      }
+  current_scope--;
+}
+
+
+/**
+ * Check whether a let will override a variable
+ * rather the define or shadow it
+ * 
+ * @param   variable  The variable index
+ * @return            Whether a let will override the variable
+ */
+int variables_let_will_override(size_t variable)
+{
+  if (variable >= variable_count)   return 0;
+  if (variables[variable] == NULL)  return 0;
+  return variables[variable]->scope == current_scope;
+}
+
+
+/**
+ * Assign a value to a variable, and define or shadow it in the process
+ * 
+ * @param   variable  The variable index
+ * @param   value     The variable's new value
+ * @return            Zero on success, -1 on error
+ */
+int variables_let(size_t variable, mds_kbdc_tree_t* restrict value)
+{
+  variable_t** new;
+  variable_t* previous;
+  
+  /* Grow the table if necessary to fit the variable. */
+  if (variable >= variable_count)
+    {
+      new = realloc(variables, (variable + 1) * sizeof(variable_t*));
+      if (new == NULL)
+	return -1;
+      variables = new;
+      memset(variables, 0, (variable + 1 - variable_count) * sizeof(variable_t*));
+      variable_count = variable + 1;
+    }
+  
+  if (variables_let_will_override(variable))
+    {
+      /* Override. */
+      mds_kbdc_tree_free(variables[variable]->value);
+      variables[variable]->value = value;
+    }
+  else
+    {
+      /* Shadow or define. */
+      previous = variables[variable];
+      variables[variable] = malloc(sizeof(variable_t));
+      if (variables[variable] == NULL)
+	return variables[variable] = previous, -1;
+      variables[variable]->value = value;
+      variables[variable]->previous = previous;
+      variables[variable]->scope = current_scope;
+    }
+  
+  return 0;
+}
+
+
+/**
+ * Get the value currently assigned to a variable
+ * 
+ * The function cannot fail, `NULL` is however returned
+ * if the variable is not defined
+ * 
+ * @param   variable  The variable index
+ * @return            The variable's value, `NULL` if not defined
+ */
+mds_kbdc_tree_t* variables_get(size_t variable)
+{
+  if (variable >= variable_count)   return NULL;
+  if (variables[variable] == NULL)  return NULL;
+  return variables[variable]->value;
+}
+
diff --git a/src/mds-kbdc/variables.h b/src/mds-kbdc/variables.h
new file mode 100644
index 0000000..26d3c72
--- /dev/null
+++ b/src/mds-kbdc/variables.h
@@ -0,0 +1,80 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef MDS_MDS_KBDC_VARIABLES_H
+#define MDS_MDS_KBDC_VARIABLES_H
+
+
+#include "parsed.h"
+#include "string.h"
+
+
+
+/**
+ * Destroy the variable storage
+ */
+void variables_terminate(void);
+
+/**
+ * Push the variable-stack, making it
+ * possible to shadow all variables
+ * 
+ * @return  Zero on success, -1 on error
+ */
+void variables_stack_push(void);
+
+/**
+ * Undo the actions of `variables_stack_push`
+ * and all additions to the variable storage
+ * since it was last called (without a
+ * corresponding call to this function)
+ */
+void variables_stack_pop(void);
+
+/**
+ * Check whether a let will override a variable
+ * rather the define or shadow it
+ * 
+ * @param   variable  The variable index
+ * @return            Whether a let will override the variable
+ */
+int variables_let_will_override(size_t variable) __attribute__((pure));
+
+/**
+ * Assign a value to a variable, and define or shadow it in the process
+ * 
+ * @param   variable  The variable index
+ * @param   value     The variable's new value
+ * @return            Zero on success, -1 on error
+ */
+int variables_let(size_t variable, mds_kbdc_tree_t* restrict value);
+
+/**
+ * Get the value currently assigned to a variable
+ * 
+ * The function cannot fail, `NULL` is however returned
+ * if the variable is not defined
+ * 
+ * @param   variable  The variable index
+ * @return            The variable's value, `NULL` if not defined
+ */
+mds_kbdc_tree_t* variables_get(size_t variable) __attribute__((pure));
+
+
+
+#endif
+