79 lines
2.8 KiB
Text
79 lines
2.8 KiB
Text
# calc.ludic - CSS's calc(), min(), max() and clamp(): + - * / and brackets over lengths (px, em, rem,
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# vw, vh, a bare number is px), percentages and plain numbers. A width, height or inset keeps its
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# percentage apart, to be taken of the room it is given; elsewhere a percentage has nothing to share.
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function ca_is(s: string) -> bool { return ca_fn_at(s, 0) != "" }
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# calc(...) worked out into ca_px and ca_pct; false (with the reason said) when it cannot be
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function ca_eval(ui_st: mut UiState, s: string) -> bool {
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ui_st.ca_s = s
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ui_st.ca_i = 0
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ui_st.ca_bad = ""
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ui_st.ca_used = 0 # this evaluation's terms come from the pool, from the start
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ui_st.ca_depth = 0
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let v = ca_factor(ui_st)
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ca_ws(ui_st)
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if ui_st.ca_bad == "" and ui_st.ca_i < len(ui_st.ca_s) { ui_st.ca_bad = "nothing after its closing )" }
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if ui_st.ca_bad != "" {
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ui_err(ui_st, `{s}: calc() expected {ui_st.ca_bad}`)
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return false
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}
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ui_st.ca_px = v.px
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ui_st.ca_pct = v.pct
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ui_st.ca_num = v.n
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ui_st.ca_bare = v.bare
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if v.bare { ui_st.ca_px = el_px(ui_st, v.n) }
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return true
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}
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property CaVal {
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px: float = 0.0
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pct: float = 0.0
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n: float = 0.0
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bare: bool = true # a plain number, which may scale a length
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}
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function ca_ws(ui_st: mut UiState) -> void {
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while ui_st.ca_i < len(ui_st.ca_s) and (ui_st.ca_s[ui_st.ca_i] == 32 or ui_st.ca_s[ui_st.ca_i] == 9 or ui_st.ca_s[ui_st.ca_i] == 10) { ui_st.ca_i += 1 }
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}
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function ca_sum(ui_st: mut UiState) -> CaVal {
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var a = ca_product(ui_st)
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while ui_st.ca_bad == "" {
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ca_ws(ui_st)
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if ui_st.ca_i >= len(ui_st.ca_s) or (ui_st.ca_s[ui_st.ca_i] != 43 and ui_st.ca_s[ui_st.ca_i] != 45) { return a }
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let minus = ui_st.ca_s[ui_st.ca_i] == 45
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ui_st.ca_i += 1
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let b = ca_product(ui_st)
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a = ca_add(ui_st, a, b, minus)
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}
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return a
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}
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function ca_add(ui_st: mut UiState, a: CaVal, b: CaVal, minus: bool) -> CaVal {
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var sign = 1.0
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if minus { sign = -1.0 }
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let r = ca_new(ui_st)
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if a.bare and b.bare {
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r.n = a.n + sign * b.n
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return r
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}
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r.bare = false
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r.px = ca_len(ui_st, a).px + sign * ca_len(ui_st, b).px
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r.pct = a.pct + sign * b.pct
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return r
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}
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# a bare number beside a length is a length in px
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function ca_len(ui_st: mut UiState, a: CaVal) -> CaVal {
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if not a.bare { return a }
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let r = ca_new(ui_st)
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r.bare = false
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r.px = el_px(ui_st, a.n)
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return r
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}
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# a term, blank, from the pool: an evaluation is over before the next begins, and what it works out is
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# copied into ca_px / ca_pct, so its records are used again by the next one (never made a frame)
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function ca_new(ui_st: mut UiState) -> CaVal {
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if ui_st.ca_used >= len(ui_st.ca_pool) { push(ui_st.ca_pool, new CaVal) }
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let r = ui_st.ca_pool[ui_st.ca_used]
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ui_st.ca_used += 1
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r.px = 0.0
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r.pct = 0.0
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r.n = 0.0
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r.bare = true
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return r
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}
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