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adrien 36fc63780a early version: modular block files, full template set, tab UI, OpenGL defaults

2026-06-19 01:18:36 +02:00

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Architecture

Stack

Pure vanilla HTML/CSS/JS — no frameworks, no build tools. MathJax v3 for LaTeX rendering is the only runtime dependency (loaded before app scripts). Eight JS modules loaded in dependency order at the end of <body>.

Load Order

index.html
  └─ style.css
  └─ lib/mathjax/tex-mml-chtml.js  → MathJax v3 (LaTeX→HTML rendering)
  └─ dom.js          → $, $id, svgNamespace, STORAGE_KEY
  └─ helpers.js      → splitValueAndUnit, rebuildSelect, refresh* functions
  └─ error.js        → showError, closeError
  └─ draw.js         → routeBetween, drawpath, shadow link system
  └─ wcblock.js      → WCBlock base (drag/drop, link system, code traversal)
  └─ blocks-algo.js  → Algorithm tab blocks (WCStart, WCEnd, WCOutput, WCDecision,
  │                    WCAssign, WCExpression, WCVarRef)
  └─ blocks-data.js  → Data & Measurement tab blocks (WCQuantity, WCUnit, WCBoolean,
  │                    WCScalar, WCString, WCArray)
  └─ blocks-proc.js  → Procedure blocks (WCProcedure, WCProcCall)
  └─ wcprogram.js    → WCProgram + block registry + registration calls
  └─ persist.js      → saveWorkspace, loadWorkspace, newWorkspace
  └─ app.js          → entry point, setupUI, main()

File Roles

`dom.js` — Global constants & DOM shortcuts

Provides app-wide constants that every module depends on:

$ — document.querySelector.bind(document) — concise single-element selector
$id — document.getElementById.bind(document) — concise ID lookup
svgNamespace — "http://www.w3.org/2000/svg" — for SVG element creation
STORAGE_KEY — "workspace" — localStorage key for persistence

`helpers.js` — Utility functions & dropdown refresh

Pure helper functions (no module dependencies beyond DOM):

splitValueAndUnit(str, defaultNum) — parses "5 km" → {numVal: 5, unitSuffix: "km"}
rebuildSelect(sel, placeholder, values, current) — replaces <select> options preserving selection
refreshQuantityOptions() — syncs all quantity-name dropdowns from wc-quantity blocks
refreshUnitOptions() — syncs unit-suffix dropdowns per datum's selected quantity
refreshDefaultUnitOptions() — syncs default-unit dropdowns per quantity's matching units
getDefaultUnitSuffix(quantityName) — looks up a quantity's default unit
refreshAll() — runs all refresh passes in dependency order
refreshVarRefOptions() — syncs varref dropdowns with Data-tab variables

`error.js` — Error modal overlay

A self-contained error modal:

showError(msg) — shows the -ACK! overlay with a message
closeError(ev) — dismisses the overlay (click backdrop, X button, or programmatic)

`draw.js` — SVG connection drawing & shadow link

Manages the two-click link system and polyline SVG paths:

EXT (25px) — distance a path extends from a hook in its exit direction
linkageFirst — tracks the first-clicked output hook during link creation
shadowPath — the dashed SVG path following the cursor during linking
routeBetween(x1, y1, x2, y2) — 45°-constrained polyline routing
resolveHook(path, which) — resolves from/to hook references on a path
getHookExit(hook, svgRect) — computes the extended control point for a hook
drawpath(path) — draws/redraws an SVG connection path between two hooks
startShadowLink(hook) — begins showing a dashed shadow path from a hook to cursor
onShadowMove(ev) — updates shadow path endpoint on mousemove
endShadowLink() — removes shadow path and stops tracking
resetLinkage() — cancels pending link and removes shadow
deleteLink(path) — removes a connection path and cleans up block flow arrays

Block files — Custom element classes

Five files define the custom element hierarchy (loaded in order):

wcblock.js — WCBlock base class:

Drag-and-drop with grid snapping
Two-click hook link system
Flow tracking (wcForeFlow, wcNextFlow)
Code generation traversal (generateCode, generateNextCode, generateOwnCode)
Selection, deletion, resize handle

blocks-algo.js — Algorithm tab blocks (WCStart, WCEnd, WCOutput, WCDecision, WCAssign, WCExpression, WCVarRef)

blocks-data.js — Data & Measurement tab blocks (WCQuantity, WCUnit, WCBoolean, WCScalar, WCString, WCArray)

blocks-proc.js — Procedure blocks (WCProcedure, WCProcCall)

Collectively they define two class hierarchies:

WCBlock (extends HTMLElement) — base for all draggable/linkable blocks:

Sets data-block attribute in constructor (used as CSS selector hook instead of listing all tag names)
Grid-snapped drag-and-drop (startDragging, dragAround, stopDragging; uses arrow functions for bound handlers)
Two-click hook link system (connectedCallback → _setupHook(hook) per hook button)
Flow tracking (wcForeFlow, wcNextFlow arrays of SVG path elements)
Code generation (generateCode(), generateNextCode())
Selection on click (.selected class, blue box-shadow ring)
Deletion via X button (top-right, shown on hover) or Delete key
X button omitted for WCStart / WCEnd; their delete() shows an error

Subclass	Purpose	Hooks	Code Output
`WCStart`	Entry point	1 output	`""`
`WCEnd`	Program exit	1 input	`""`
`WCOutput`	Print statement	1 input, 1 output	`printf("...");`
`WCDecision`	Conditional branch	1 input, 2 output (yes/no), 1 data in (bool)	`if(...) {...} else {...}`
`WCAssign`	Variable assignment	1 input, 1 output, 1 data in (scalar), optional data in (index)	`name = value;`
`WCQuantity`	SI quantity definition	none (inert hook)	typedef comment
`WCUnit`	SI unit definition	none (inert hook)	unit comment
`WCBoolean`	Boolean variable	none (inert hook)	`int name = 0/1;`
`WCScalar`	Scalar variable with quantity + unit	none (inert hook)	`type name = value;`
`WCString`	String variable (char* + length)	none (inert hook)	`string name = {"text", len};`
`WCArray`	Typed C array	none	`type name[] = {values};`
`WCVarRef`	Read-only variable reference in algorithm view	1 data out	`""` (visual only)
`WCExpression`	MathJax-rendered expression	dynamic data-in (per variable), 1 data out	`double name = formula;`
`WCProcedure`	Procedure definition with typed params	none (inert hook)	`""` (comments only)
`WCProcCall`	Procedure call	1 input, 1 output, dynamic data in/out	`proc(args);`

WCProgram (extends HTMLElement directly) — root container:

build() — creates mandatory START/END blocks
makeNode(tag) — deep-clones a template by registry lookup, assigns unique ID
newNode(tag, parent) — creates a node and appends to the given parent (or registry default)
Convenience methods: newDecisionNode, newExpressionNode, newVarRefNode, newOutputNode, newProcCallNode, newUnitNode, newQuantityNode, newBooleanNode, newScalarNode, newStringNode, newArrayNode, newProcedureNode
generateCode() — traverses all blocks and produces complete C source

`persist.js` — Workspace persistence (localStorage)

Serialises and deserialises the full workspace:

saveBlockData(block) — reads position + type-specific data from a block
saveWorkspace() — serialises all blocks + connections to localStorage
restoreBlock(info) — deep-clones a template and restores data onto it
loadWorkspace() — deserialises and reconstructs the workspace
newWorkspace() — clears localStorage and reloads the page

`app.js` — Entry point & orchestration

Wires everything together:

createDefaultMeasurements() — pre-populates 22 SI quantities and 22 SI units
switchTab(name) — activates a tab by name
setupUI() — registers all event listeners (delegation pattern, no inline onclick)
main() — bootstrap: builds start/end, creates defaults, loads workspace, sets up UI

Data Flow

Link System (Two-Click)

User clicks output hook
  → linkageFirst = { block, hook }
  → startShadowLink(hook) — dashed path follows cursor

User clicks input hook (different block)
  → checks link-type match (logic↔logic, data↔data)
  → checks data-type match for data links
  → creates SVG <path class="flow" or "flow-data">
  → pushes to wcForeFlow / wcNextFlow arrays
  → calls drawpath(path)
  → calls resetLinkage()

User clicks empty space or same block
  → resetLinkage() cancels pending link

Drag-and-Drop

User mousedown on block
  → startDragging records initial position
  → sets document.onmousemove = this._dragBound
  → sets document.onmouseup = this._stopBound

Mouse moves
  → dragAround snaps position to --grid-size increments
  → redraws all wcNextFlow + wcForeFlow paths

Mouse up
  → stopDragging clears document handlers

Code Generation

WCProgram.generateCode()
  → Gathers all wc-boolean + wc-scalar blocks → usedQuantities, usedUnits sets
  → Filters wc-quantity blocks to only used quantities → typedefs
  → Filters wc-unit blocks to only used units → unit comments
  → Generates variable declarations from datums
  → Walks flow graph from START via generateNextCode()
  → Writes to #c-code textarea

Decision blocks handle convergence: BFS per branch + intersection to detect shared blocks. Branch-exclusive code in if/else, shared code after.

Persistence

Save:  saveWorkspace() → JSON → localStorage["workspace"]
Load:  loadWorkspace() → localStorage["workspace"] → JSON → DOM reconstruction
New:   newWorkspace()  → confirm() → localStorage.removeItem → location.reload()

Key Patterns

Event Delegation (setupUI in app.js)

All toolbar and tab-bar events use delegated listeners on static parent elements, matching e.target.closest("button"). This avoids per-button listeners.

Custom Element Lifecycle

Each WCBlock subclass calls super.connectedCallback() first, which installs hook click handlers (guarded by _hooksSetup flag). Subclasses then cache their child DOM elements in this._el.* to avoid repeated querySelector calls.

SVG Path Routing

Paths are constrained to {0°, 45°, 90°} angles using routeBetween(). Each path segment:

Extends EXT (25px) from source hook in its data-exit direction
Routes with 45°-constrained polyline to target hook's exit point
Approaches target hook from its data-exit direction

Hook Visual System

Logic output hooks (data-direction="out", data-link-type="logic"): solid blue circles, scale on hover
Logic input hooks (data-direction="in", data-link-type="logic"): dashed gray outlines, fill blue on hover
Data output hooks (data-direction="out", data-link-type="data"): solid green circles, scale on hover
Data input hooks (data-direction="in", data-link-type="data"): light green dashed outlines, fill green on hover
Side hooks (left/right): force horizontal path exits
Top/bottom hooks: force vertical path exits
Inert hooks (no data-direction): 20% opacity, non-interactive

Link Deletion

Clicking an SVG connection path (class flow) deletes it:

Removes path from fromElement.wcNextFlow and toElement.wcForeFlow
Removes from DOM; nulls out custom properties
Delegated click handler on #connections in app.js

Tab System

Tab	Pane ID	Contains	Toolbar Buttons
Algorithm	`pane-algorithm`	Flowchart blocks (start, end, output, decision, expression, varref)	new decision, new expression, new variable, new output
Data	`pane-data`	Boolean/scalar/string variable blocks	new variable
Measurements	`pane-measurements`	Quantity definitions + unit definitions	new quantity, new unit

MathJax Integration (WCExpression)

WCExpression uses MathJax v3 (tex-mml-chtml.js) for client-side LaTeX rendering:

Config: inlineMath ( $...$ ), displayMath ($$...$$), enableMenu: false, elements: [] (manual typeset only)
Rendering: MathJax.tex2chtmlPromise(latex) returns an HTML DOM node appended to .expr-rendered
Variable parsing: LaTeX source is stripped of \commands, braces, operators, and numbers; remaining tokens are deduplicated and filtered against known function/Greek names to produce a list of variable names
Dynamic hooks: For each parsed variable, a <button class="hook"> is created in .expr-varhooks with data-link-type="data", data-type="scalar", and wired through _setupHook()
Fallback: If MathJax is unavailable, .expr-rendered shows the raw LaTeX text
Persistence: Only the LaTeX string is saved/restored; variable hooks are regenerated from it on load

Data Type System (WCBoolean / WCScalar / WCString)

Variable blocks come in three distinct types, not interchangeable:

WCBoolean (wc-boolean): A boolean variable. Has a name and a true/false value selector. No unit, no SI conversion, no quantity dropdown. Generates int name = 0/1;.
WCScalar (wc-scalar): A typed scalar variable. Has a name, numeric value, unit dropdown, and quantity selector with SI conversion display. Generates quantityName name = siValue;.
WCString (wc-string): A string variable. Has a name and a text value. Generates string name = {"text", length};. The string struct ({char *data; long int length;}) is emitted once before variable declarations when any string blocks exist.

Unlike the previous unified WCDatum block, there is no way to switch between types — they are separate custom elements with distinct templates and classes.

WCExpression (wc-expression) is a flowchart block (not a variable) with dynamic data-input hooks that match "scalar" data type for data-flow linking.

SI Measurement System

7 base dimensions indexed dim-0..dim-6: L, M, T, I, Θ, N, J
22 default quantities (length, mass, time, etc.) and 22 default units (m, kg, s, etc.)
Units support recursive factor resolution: 1 in = 0.0254 m → getSiFactor() follows references
Cycle detection via visited Set in getSiFactor()
Datum values auto-convert to SI: 5 km → 5000 in generated code
Quantity blocks live in the Data tab; Unit blocks live in the Measurements tab
Only quantities and units actually referenced by datum blocks appear in generated code

Performance Notes

_gridSize fetched once from CSS computed style, then cached per block (null sentinel)
Bound functions _dragBound / _stopBound created once in constructor, reused across drags
$id uses native getElementById instead of CSS selector parsing
Container-scoped querySelectorAll avoids #id descendant selectors
Child elements cached in this._el.* during connectedCallback
Deferred setTimeout(..., 0) for initial dropdown population avoids layout thrash

Known Limitations

No duplicate link detection (same source→target hook pair creates duplicate paths)
Data hooks only support "scalar" type for now; no mixed-type data flow (expression varhooks hard-coded to scalar)
No delete functionality for individual blocks
Datum value parsing only handles "number suffix" format (no expressions)
Code generation walks linear flow; only decision blocks handle branching
Tab-hidden SVG paths render at wrong positions (hidden tab getBoundingClientRect returns zeros)

Optimization & Simplification Notes

`data-block` CSS attribute

All WCBlock subclasses set data-block in the constructor. This replaces tedious tag-name selector lists (e.g. wc-start, wc-end, wc-output, ...) throughout style.css, app.js, and persist.js with a single [data-block] selector.

Dead code removed

WCBlock.collectDescendants() — was never called (BFS for downstream blocks; the decision-block codegen handles convergence inline)
Duplicate CSS rule wc-expression .expr-varhooks .hook[data-direction="in"] — covered by .expr-varhooks .hook

Persistence fixes

Data connections: save/load now handles both path.flow (logic) and path.flow-data (data) SVG paths. Previously, data links were silently lost.
Refresh order: refreshAll() runs after all blocks and connections are restored, ensuring varref dropdowns and hook data-type attributes reflect the full state.

Render deduplication

WCExpression._renderFormula() uses a shared done() helper to call _parseVariables + _rebuildVarHooks after both the MathJax and the fallback rendering path, instead of duplicating the calls.

Refresh consistency

newBooleanNode(), newScalarNode(), and newStringNode() now call refreshVarRefOptions() so existing varref dropdowns update immediately when new variables are created. The explicit refreshVarRefOptions() calls in app.js toolbar handlers were removed as redundant.

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