Add highlight component

Author: nkanderson

static/highlight.js

@@ -0,0 +1,83 @@
+// Copyright 2018 The Rustw Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+import React from 'react';
+
+export const Highlight = (props) => {
+    const src_line_prefix = 'src_line_';
+    const highlight = props.highlight;
+    const is_valid_highlight = validate_highlight(highlight);
+
+    if (!is_valid_highlight) {
+        return null;
+    }
+
+    const lhs = (highlight.column_start - 1);
+    const rhs = (highlight.column_end - 1);
+    const highlight_specs = make_highlight(src_line_prefix, highlight.line_start, lhs, rhs);
+    if (highlight_specs) {
+        const { top, left, width } = highlight_specs;
+        const style = {
+            top: top,
+            left: left,
+            width: width,
+        }
+        return <div className="selected floating_highlight" key={highlight.line_start} style={style}>&nbsp;</div>;
+    }
+
+    return null;
+}
+
+function make_highlight(src_line_prefix, line_number, left, right) {
+    const line_div = $("#" + src_line_prefix + line_number);
+
+    // TODO: get adjust variable as prop through diffIndent in FileResult
+    // if Highlight component is to be used in the SearchResults component
+    // const adjust = line_div.data('adjust');
+    // if (adjust) {
+    //     left -= adjust;
+    //     right -= adjust;
+    // }
+
+    left *= CHAR_WIDTH;
+    right *= CHAR_WIDTH;
+    if (right === 0) {
+        right = line_div.width();
+    }
+
+    let width = right - left;
+    const paddingLeft = parseInt(line_div.css("padding-left"));
+    const paddingTop = parseInt(line_div.css("padding-top"));
+    if (left >= 0) {
+        left -= paddingLeft;
+    } else {
+        width += paddingLeft;
+    }
+
+    const position = line_div.position();
+    if (position) {
+        position.left += left;
+        position.top += paddingTop;
+        return { top: position.top, left: position.left, width };
+    }
+    // If no position, don't render the highlight
+    return null;
+}
+
+// TODO: this could maybe be validated in app.js, at srcHighlight declaration
+function validate_highlight(highlight) {
+    const required_keys = ['line_start', 'line_end', 'column_start', 'column_end'];
+    const has_keys = required_keys.reduce((acc, k) => {
+        return acc && highlight[k] !== undefined;
+    }, true);
+
+    if (!has_keys || highlight.column_start <= 0) {
+        return false;
+    }
+    return true;
+}