Return true if the characters in str, interpreted as a string, start with prefix.

Return chars segmented as a list of strings each paired with a HighlightT. The string is the text to be highlighted and the HighlightT determines the color. HighlightT to color mapping is done in the render function.

Initial state of the code editor.

Returns the intersection of two intervals each defining the end points of a raster scan (ascending order X first then Y), or None if there is no intersection.

Active pattern helper that matches if a list of chars starts with startP. If it matches the return value is a pair: the first character and the string of characters matching inMatchP the list of chars from the first character that does not match inMatchP. or None if the first character does not match startP. NB - this cannot itself be an active pattern since startP and inMatchP are not literals.

Handles editor mouse events. evtype is the type of event (e.g., click, mousemove). dispatch is the function to call to update the model. ev is the mouse event from the browser.

Memoizes the function as a react component so that it is not called unless the props change. In addition, if the function is not called, the React DOM from the function result is not updated. This is important for performance when the react DOM is large.

Renders the complete code editor with syntax highlighting and error indication. The editor is rendered in a div with a fixed size as specified in the CSS Height and Width props. The height of the editor is rounded to fit an integral number of lines. The editor is scrollable in both X and Y directions. CoceEditorModel is the model for the code editor, and includes info about the lines of code, the cursor position, and any errors.

Renders the line numbers in the left margin of the code editor. xPosition is the X position of the left margin within the scrolling editor div It changes to ensure the left margin stays fixed at the left of the editor. The number of lines is determined by the number of lines in the model.

Renders a single line of code in the editor, with optional cursor and error indication.

Some ad hoc test data for the code editor used during development. Change as needed, this is not a unit test.

Main editor model update function, called from Elmish main update when a CodeEditorMsg Message is received. This allows additional Code Editor messages to be added here in the future without changing the main update function. Note that the message type must still be changed in ModelType.fs since F# does not support forward type references even to an opaque type. NB - There is a way to get forward references - by parametrising the Model type - that is theoretically neat, and possible, but in practice it is too messy to implement because type parameters would then decorate the whole code base.

Updates the Editor model with the new cursor position based on mouse coordinates. xMouse and yMouse are the mouse coordinates. xMouse specifies the column position in the line at which new chars are inserted xMouse - 1 is the column that is deleted on backspace. Model is the whole Issie Model - of which CodeEditorModel is one field.

Implements a model update for a key press event. The keyCode is the code of the key pressed. Normally, this is a character code, but it can also be a special key code (e.g., backspace). Character codes are inserted. Special codes are handled differently. Lines and CursorPos are updated accordingly.

Active Pattern that matches if str starts with a given character. Returns the remaining string if it does. NB - charToMatch must be a literal for this to work

Active Pattern that matches if str starts with an identifier. Returns the identifier and the remaining string if it does.

Returns as many characters not part of any other active pattern match as possible. This must be adjusted to match the otehr active patterns. Note that doing this without a this pattern, using a default for each character, would be inefficient since it would require a match for each character in the string. In addition it would require another pass to common up sequences of characters. However that would make the code more robust, and perhaps it would be better to do this.

Active Pattern that matches if str starts with a number. Returns the number and the remaining string if it does.

Active Pattern that matches if a char list starts with any of the prefixes in a list. Returns the prefix and the remaining characters if it does. NB - prefixL must be a literal for this to work

Active Pattern that matches if str starts with a string literal. A string literal is a string starting with a quote and ending with a quote. Returns the non quote part of the string literal and the remainder of str if it does. The closing quote is not removed from str.