Spreadsheet: Let the cells know their own position in the sheet

7 files changed, 227 insertions, 22 deletions

diff --git a/Applications/Spreadsheet/Cell.h b/Applications/Spreadsheet/Cell.h
index 3942d83c94..04c10a66c0 100644
--- a/Applications/Spreadsheet/Cell.h
+++ b/Applications/Spreadsheet/Cell.h
@@ -30,6 +30,7 @@
 #include "ConditionalFormatting.h"
 #include "Forward.h"
 #include "JSIntegration.h"
+#include "Position.h"
 #include <AK/String.h>
 #include <AK/Types.h>
 #include <AK/WeakPtr.h>
@@ -37,20 +38,22 @@
 namespace Spreadsheet {
 
 struct Cell : public Weakable<Cell> {
-    Cell(String data, WeakPtr<Sheet> sheet)
+    Cell(String data, Position position, WeakPtr<Sheet> sheet)
         : dirty(false)
         , data(move(data))
         , kind(LiteralString)
         , sheet(sheet)
+        , m_position(move(position))
     {
     }
 
-    Cell(String source, JS::Value&& cell_value, WeakPtr<Sheet> sheet)
+    Cell(String source, JS::Value&& cell_value, Position position, WeakPtr<Sheet> sheet)
         : dirty(false)
         , data(move(source))
         , evaluated_data(move(cell_value))
         , kind(Formula)
         , sheet(sheet)
+        , m_position(move(position))
     {
     }
 
@@ -63,6 +66,13 @@ struct Cell : public Weakable<Cell> {
     void set_type(const CellType*);
     void set_type_metadata(CellTypeMetadata&&);
 
+    const Position& position() const { return m_position; }
+    void set_position(Position position, Badge<Sheet>)
+    {
+        dirty = true;
+        m_position = move(position);
+    }
+
     const Format& evaluated_formats() const { return m_evaluated_formats; }
     const Vector<ConditionalFormat>& conditional_formats() const { return m_conditional_formats; }
     void set_conditional_formats(Vector<ConditionalFormat>&& fmts)
@@ -99,6 +109,7 @@ struct Cell : public Weakable<Cell> {
     Vector<WeakPtr<Cell>> referencing_cells;
     const CellType* m_type { nullptr };
     CellTypeMetadata m_type_metadata;
+    Position m_position;
 
     Vector<ConditionalFormat> m_conditional_formats;
     Format m_evaluated_formats;
diff --git a/Applications/Spreadsheet/JSIntegration.cpp b/Applications/Spreadsheet/JSIntegration.cpp
index f393093d8e..26cc864cb7 100644
--- a/Applications/Spreadsheet/JSIntegration.cpp
+++ b/Applications/Spreadsheet/JSIntegration.cpp
@@ -82,6 +82,7 @@ void SheetGlobalObject::initialize()
 {
     GlobalObject::initialize();
     define_native_function("parse_cell_name", parse_cell_name, 1);
+    define_native_function("current_cell_position", current_cell_position, 0);
 }
 
 JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::parse_cell_name)
@@ -106,6 +107,36 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::parse_cell_name)
     return object;
 }
 
+JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::current_cell_position)
+{
+    if (vm.argument_count() != 0) {
+        vm.throw_exception<JS::TypeError>(global_object, "Expected no arguments to current_cell_position()");
+        return {};
+    }
+
+    auto* this_object = vm.this_value(global_object).to_object(global_object);
+    if (!this_object)
+        return JS::js_null();
+
+    if (StringView("SheetGlobalObject") != this_object->class_name()) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "SheetGlobalObject");
+        return {};
+    }
+
+    auto sheet_object = static_cast<SheetGlobalObject*>(this_object);
+    auto* current_cell = sheet_object->m_sheet.current_evaluated_cell();
+    if (!current_cell)
+        return JS::js_null();
+
+    auto position = current_cell->position();
+
+    auto object = JS::Object::create_empty(global_object);
+    object->put("column", JS::js_string(vm, position.column));
+    object->put("row", JS::Value((unsigned)position.row));
+
+    return object;
+}
+
 WorkbookObject::WorkbookObject(Workbook& workbook)
     : JS::Object(*JS::Object::create_empty(workbook.global_object()))
     , m_workbook(workbook)
diff --git a/Applications/Spreadsheet/JSIntegration.h b/Applications/Spreadsheet/JSIntegration.h
index 9bddb1e25e..46886f9529 100644
--- a/Applications/Spreadsheet/JSIntegration.h
+++ b/Applications/Spreadsheet/JSIntegration.h
@@ -45,6 +45,7 @@ public:
     virtual void initialize() override;
 
     JS_DECLARE_NATIVE_FUNCTION(parse_cell_name);
+    JS_DECLARE_NATIVE_FUNCTION(current_cell_position);
 
 private:
     Sheet& m_sheet;
diff --git a/Applications/Spreadsheet/Position.h b/Applications/Spreadsheet/Position.h
new file mode 100644
index 0000000000..358ab9c1f6
--- /dev/null
+++ b/Applications/Spreadsheet/Position.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Types.h>
+
+namespace Spreadsheet {
+
+struct Position {
+    String column;
+    size_t row { 0 };
+
+    bool operator==(const Position& other) const
+    {
+        return row == other.row && column == other.column;
+    }
+
+    bool operator!=(const Position& other) const
+    {
+        return !(other == *this);
+    }
+};
+
+}
diff --git a/Applications/Spreadsheet/Spreadsheet.cpp b/Applications/Spreadsheet/Spreadsheet.cpp
index 0519434c1f..254b77ae71 100644
--- a/Applications/Spreadsheet/Spreadsheet.cpp
+++ b/Applications/Spreadsheet/Spreadsheet.cpp
@@ -245,12 +245,12 @@ RefPtr<Sheet> Sheet::from_json(const JsonObject& object, Workbook& workbook)
         OwnPtr<Cell> cell;
         switch (kind) {
         case Cell::LiteralString:
-            cell = make<Cell>(obj.get("value").to_string(), sheet->make_weak_ptr());
+            cell = make<Cell>(obj.get("value").to_string(), position, sheet->make_weak_ptr());
             break;
         case Cell::Formula: {
             auto& interpreter = sheet->interpreter();
             auto value = interpreter.call(parse_function, json, JS::js_string(interpreter.heap(), obj.get("value").as_string()));
-            cell = make<Cell>(obj.get("source").to_string(), move(value), sheet->make_weak_ptr());
+            cell = make<Cell>(obj.get("source").to_string(), move(value), position, sheet->make_weak_ptr());
             break;
         }
         }
diff --git a/Applications/Spreadsheet/Spreadsheet.h b/Applications/Spreadsheet/Spreadsheet.h
index 3207398ec8..8d8ad29acc 100644
--- a/Applications/Spreadsheet/Spreadsheet.h
+++ b/Applications/Spreadsheet/Spreadsheet.h
@@ -41,21 +41,6 @@
 
 namespace Spreadsheet {
 
-struct Position {
-    String column;
-    size_t row { 0 };
-
-    bool operator==(const Position& other) const
-    {
-        return row == other.row && column == other.column;
-    }
-
-    bool operator!=(const Position& other) const
-    {
-        return !(other == *this);
-    }
-};
-
 class Sheet : public Core::Object {
     C_OBJECT(Sheet);
 
@@ -89,7 +74,7 @@ public:
         if (auto cell = at(position))
             return *cell;
 
-        m_cells.set(position, make<Cell>(String::empty(), make_weak_ptr()));
+        m_cells.set(position, make<Cell>(String::empty(), position, make_weak_ptr()));
         return *at(position);
     }
 
diff --git a/Base/res/js/Spreadsheet/runtime.js b/Base/res/js/Spreadsheet/runtime.js
index df74a37d1c..67e66307e0 100644
--- a/Base/res/js/Spreadsheet/runtime.js
+++ b/Base/res/js/Spreadsheet/runtime.js
@@ -1,8 +1,82 @@
+// FIXME: Figure out a way to document non-function entities too.
+class Position {
+    constructor(column, row, sheet) {
+        this.column = column;
+        this.row = row;
+        this.sheet = sheet ?? thisSheet;
+        this.name = `${column}${row}`;
+    }
+
+    static from_name(name) {
+        let sheet = thisSheet;
+        let obj = sheet.parse_cell_name(name);
+        return new Position(obj.column, obj.row, sheet);
+    }
+
+    up(how_many) {
+        how_many = how_many ?? 1;
+        const row = Math.max(0, this.row - how_many);
+        return new Position(this.column, row, this.sheet);
+    }
+
+    down(how_many) {
+        how_many = how_many ?? 1;
+        const row = Math.max(0, this.row + how_many);
+        return new Position(this.column, row, this.sheet);
+    }
+
+    left(how_many) {
+        how_many = how_many ?? 1;
+        const column = Math.min(
+            "Z".charCodeAt(0),
+            Math.max("A".charCodeAt(0), this.column.charCodeAt(0) - how_many)
+        );
+        return new Position(String.fromCharCode(column), this.row, this.sheet);
+    }
+
+    right(how_many) {
+        how_many = how_many ?? 1;
+        const column = Math.min(
+            "Z".charCodeAt(0),
+            Math.max("A".charCodeAt(0), this.column.charCodeAt(0) + how_many)
+        );
+        return new Position(String.fromCharCode(column), this.row, this.sheet);
+    }
+
+    with_column(value) {
+        return new Position(value, this.row, this.sheet);
+    }
+
+    with_row(value) {
+        return new Position(this.column, value, this.sheet);
+    }
+
+    in_sheet(the_sheet) {
+        return new Position(this.column, this.row, sheet(the_sheet));
+    }
+
+    value() {
+        return this.sheet[this.name];
+    }
+
+    valueOf() {
+        return value();
+    }
+
+    toString() {
+        return `<Cell at ${this.name}>`;
+    }
+}
+
 function range(start, end, columnStep, rowStep) {
     columnStep = integer(columnStep ?? 1);
     rowStep = integer(rowStep ?? 1);
-    start = parse_cell_name(start) ?? { column: "A", row: 0 };
-    end = parse_cell_name(end) ?? start;
+    if (!(start instanceof Position)) {
+        start = parse_cell_name(start) ?? { column: "A", row: 0 };
+    }
+    if (!(end instanceof Position)) {
+        end = parse_cell_name(end) ?? start;
+    }
 
     if (end.column.length > 1 || start.column.length > 1)
         throw new TypeError("Only single-letter column names are allowed (TODO)");
@@ -172,6 +246,21 @@ function stddev(cells) {
     return Math.sqrt(variance(cells));
 }
 
+// Lookup
+
+function row() {
+    return thisSheet.current_cell_position().row;
+}
+
+function column() {
+    return thisSheet.current_cell_position().column;
+}
+
+function here() {
+    const position = current_cell_position();
+    return new Position(position.column, position.row, thisSheet);
+}
+
 // Cheat the system and add documentation
 range.__documentation = JSON.stringify({
     name: "range",
@@ -382,3 +471,42 @@ stddev.__documentation = JSON.stringify({
         'stddev(range("A0", "C4"))': "Calculate the standard deviation of the values in A0:C4",
     },
 });
+
+row.__documentation = JSON.stringify({
+    name: "row",
+    argc: 0,
+    argnames: [],
+    doc: "Returns the row number of the current cell",
+    examples: {},
+});
+
+column.__documentation = JSON.stringify({
+    name: "column",
+    argc: 0,
+    argnames: [],
+    doc: "Returns the column name of the current cell",
+    examples: {},
+});
+
+here.__documentation = JSON.stringify({
+    name: "here",
+    argc: 0,
+    argnames: [],
+    doc:
+        "Returns an object representing the current cell's position, see `Position` below.\n\n" +
+        "## Position\na `Position` is an object representing a given cell position in a given sheet.\n" +
+        "### Methods:\n- `up(count = 1)`: goes up count cells, or returns the top position if at the top\n" +
+        "- `down(count = 1)`: goes down count cells\n" +
+        "- `left(count = 1)`: Goes left count cells, or returns the leftmost position if the edge\n" +
+        "- `right(count = 1)`: Goes right count cells.\n" +
+        "- `with_row(row)`: Returns a Position with its column being this object's, and its row being the provided the value.\n" +
+        "- `with_column(column)`: Similar to `with_row()`, but changes the column instead.\n" +
+        "- `in_sheet(the_sheet)`: Returns a Position with the same column and row as this one, but with its sheet being `the_sheet`.\n" +
+        "- `value()`: Returns the value at the position which it represents, in the object's sheet (current sheet by default).\n\n" +
+        "**NOTE**: Currently only supports single-letter column names",
+    examples: {
+        "here().up().value()": "Get the value of the cell above this one",
+        "here().up().with_column('A')":
+            "Get a Position above this one in column A, for instance, evaluates to A2 if run in B3.",
+    },
+});