First part for adding history to the user input.

Change-Id: I9d2ff28641f0d3b7fe382a765ad8cc084840c2ef

app/app.cpp

@@ -5,35 +5,11 @@ extern "C" {
 }
 
 #include <poincare.h>
+#include "../poincare/src/layout/string_layout.h"
 
 #include "utils.h"
 
-void draw_lines_from_center() {
-  KDCoordinate width = SCREEN_WIDTH;
-  KDCoordinate height = SCREEN_HEIGHT;
-
-  KDColor c = 0xFF;
-
-  KDPoint center = KDPointMake(width/2, height/2);
-  int step = 2;
-
-  for (KDCoordinate x=0; x<width; x+=step) {
-    KDDrawLine(center, KDPointMake(x,0), c);
-    ion_sleep();
-  }
-  for (KDCoordinate y=0; y<height; y+=step) {
-    KDDrawLine(center, KDPointMake(width-1,y), c);
-    ion_sleep();
-  }
-  for (KDCoordinate x=0; x<width; x+=step) {
-    KDDrawLine(center, KDPointMake(width-1-x,height-1), c);
-    ion_sleep();
-  }
-  for (KDCoordinate y=0; y<height; y+=step) {
-    KDDrawLine(center, KDPointMake(0,height-1-y), c);
-    ion_sleep();
-  }
-}
+const char* kParsingErrorMessage = "PARSING ERROR";
 
 void plot(Expression * e, float xMin, float xMax, float yMin, float yMax) {
   Context plotContext;
@@ -54,44 +30,129 @@ void plot(Expression * e, float xMin, float xMax, float yMin, float yMax) {
   }
 }
 
-void funnyPlot() {
-  Expression * e = Expression::parse((char *)"1/x");
-  plot(e, 1.0f, 4.0f, 0.0f, 1.0f);
-  delete e;
+//////////////////////////////////////////////////////
+
+#define INPUT_MEMORY 15
+
+typedef struct user_expression_t {
+  char* text_input;
+  Expression* expression;
+  Expression* simplified;
+  ExpressionLayout* expression_layout;
+  ExpressionLayout* simplified_layout;
+} user_expression_t;
+
+class UserExpressions {
+  public:
+    UserExpressions() {
+      m_numberOfExpressions = 0;
+      m_position = INPUT_MEMORY;
+      for (int i=0; i<INPUT_MEMORY; i++) {
+        m_expressions[i] = {nullptr, nullptr, nullptr, nullptr, nullptr};
+      }
+    }
+
+    // Adds a user expression as the most recent one.
+    void append_expression(user_expression_t user_expression) {
+      if (m_numberOfExpressions < INPUT_MEMORY) {
+        m_numberOfExpressions++;
+      }
+      m_position = (m_position + 1) % INPUT_MEMORY;
+      if (m_position < 0) {
+        m_numberOfExpressions += INPUT_MEMORY;
+      }
+
+      // The circular buffer is full, now we have to erase stuff.
+      if (m_numberOfExpressions == INPUT_MEMORY) {
+        user_expression_t tmp = m_expressions[m_position];
+        if (tmp.text_input) {
+          free(tmp.text_input);
+          if (tmp.expression) {
+            free(tmp.expression);
+            if (tmp.expression_layout) {
+              free(tmp.expression_layout);
+            }
+            if (tmp.simplified && tmp.simplified != tmp.expression) {
+              free(tmp.simplified);
+              if (tmp.simplified_layout) {
+                free(tmp.simplified_layout);
+              }
+            }
+          }
+        }
+      }
+      m_expressions[m_position] = user_expression;
+    }
+
+    // Gets the i th latest expression.
+    user_expression_t get_expression(uint8_t index) {
+      //assert(index < m_numberOfExpressions);
+      int pos = (m_position - index) % INPUT_MEMORY;
+      if (pos < 0) {
+        pos += INPUT_MEMORY;
+      }
+      return m_expressions[pos];
+    }
+
+    uint8_t numberOfExpressions() {
+      return m_numberOfExpressions;
+    }
+
+  private:
+    uint8_t m_numberOfExpressions;
+    uint8_t m_position;
+    user_expression_t m_expressions[INPUT_MEMORY];
+};
+
+/////////////////////////////////////////////////
+
+static user_expression_t create_user_input(char* text) {
+  user_expression_t user_expression = {text, nullptr, nullptr, nullptr, nullptr};
+  user_expression.expression = Expression::parse(user_expression.text_input);
+  if (user_expression.expression) {
+    user_expression.expression_layout = user_expression.expression->createLayout();
+    user_expression.simplified = user_expression.expression->simplify();
+    user_expression.simplified_layout = user_expression.simplified->createLayout();
+  } else {
+    user_expression.expression_layout =
+      new StringLayout(kParsingErrorMessage, strlen(kParsingErrorMessage));
+  }
+  return user_expression;
+}
+
+static int16_t print_user_input(user_expression_t user_expression, int16_t yOffset) {
+  if (user_expression.expression_layout) {
+    int16_t height = user_expression.expression_layout->size().height;
+    if (yOffset + height < SCREEN_HEIGHT) {
+      user_expression.expression_layout->draw(KDPointMake(0, yOffset));
+    }
+    yOffset += height;
+  }
+  if (user_expression.simplified_layout) {
+    int16_t height = user_expression.simplified_layout->size().height;
+    if (yOffset + height < SCREEN_HEIGHT) {
+      int16_t xOffset = SCREEN_WIDTH - user_expression.simplified_layout->size().width;
+      user_expression.simplified_layout->draw(KDPointMake(xOffset, yOffset));
+    }
+    yOffset += height;
+  }
+  return yOffset;
 }
 
 static void interactive_expression_parsing() {
+  UserExpressions user_inputs;
   while (1) {
-    char * text_input = get_text();
-    clear_screen();
-    Expression * e = Expression::parse(text_input);
-    if (e) {
-      ExpressionLayout * l = e->createLayout();
-      int16_t yOffset = 10;
-      if (l) {
-        l->draw(KDPointMake(0, yOffset));
-        yOffset += l->size().height;
-        delete l;
-      }
-      Expression * simplified = e->simplify();
-      // Print the simplification.
-      if (simplified) {
-        ExpressionLayout * simplified_l = simplified->createLayout();
-        if (simplified_l) {
-          int16_t xOffset = SCREEN_WIDTH - simplified_l->size().width;
-          simplified_l->draw(KDPointMake(xOffset, yOffset));
-          delete simplified_l;
-        }
-        if (simplified != e) {
-          delete simplified;
-        }
-      }
-      delete e;
-    } else {
-      KDDrawString("PARSING ERROR", KDPointMake(10,10), 0);
+    text_event_t text_event = get_text(nullptr);
+    if (text_event.event == EQUAL) {
+      user_inputs.append_expression(create_user_input(text_event.text));
+    }
+    int16_t yOffset = 0;
+    for (int i=0; i<user_inputs.numberOfExpressions(); i++) {
+      yOffset = print_user_input(user_inputs.get_expression(i), yOffset);
+      if (yOffset>SCREEN_HEIGHT) {
+        break;
+      }
     }
-    // We dealocate the memory allocated by get_text;
-    free(text_input);
   }
 }
 

app/utils.cpp

@@ -1,10 +1,12 @@
 extern "C" {
+#include <assert.h>
 #include <kandinsky.h>
 #include <stdlib.h>
 #include <string.h>
-#include <ion.h>
 }
 
+#include "utils.h"
+
 #define PROMPT_HEIGHT 30
 
 void clear_screen() {
@@ -105,18 +107,27 @@ static int get_trig_input(char* input) {
   }
 }
 
-char* get_text() {
+text_event_t get_text(char* txt) {
   char input[255] = {0};
   int index = 0;
   int max = 0;
   input[max] = ' ';
   input[max+1] = '\0';
+  text_event_t text_event = {nullptr, ERROR};
+
+  if (txt != nullptr) {
+   assert(false);
+  }
 
   while (1) {
     clear_prompt();
     print_prompt(input, index);
     ion_event_t event = ion_get_event();
     if (event == EQUAL) {
+      input[max] = '\0';
+      text_event.event = EQUAL;
+      text_event.text = (char*) malloc(sizeof(char) * (index + 1));
+      memcpy(text_event.text, input, (size_t) (index + 1));
       break;
     } else if (event == LEFT_ARROW) {
       index--;
@@ -158,8 +169,5 @@ char* get_text() {
   }
   
   clear_prompt();
-  input[max] = '\0';
-  char* output = (char*) malloc(sizeof(char) * (index + 1));
-  memcpy(output, input, (size_t) (index + 1));
-  return output;
+  return text_event;
 }

app/utils.h

@@ -1,9 +1,21 @@
 #ifndef APP_UTILS_H
 #define APP_UTILS_H
 
-/* Returns a pointer to an input text, allocated by the functions (it is thus
- * the caller's role to free it). */
-char* get_text();
+extern "C" {
+#include <ion.h>
+}
+
+typedef struct {
+  char* text;
+  ion_event_t event;
+} text_event_t;
+
+/* Returns a pointer to an input text allocated by the functions.
+ * Also returns an event, which is its return reason.
+ *
+ * This function can get a text to work on instead of starting from an empty
+ * string. */
+text_event_t get_text(char* txt);
 
 void clear_screen();